# The On-Line Encyclopedia of Integer Sequences

March 10, 2009 10:37 AM Subscribe

Ever wondered what comes next, and why? The On-Line Encyclopedia of Integer Sequences has the answers. (Previously.)

sorta unrelated question--that dumb new movie with Nic Cage and the numbers of all the people killed in disasters, with the final number being like, everyone, could you analyzed that sequence for real to figure out what numbers were what?

posted by Ironmouth at 10:44 AM on March 10, 2009

posted by Ironmouth at 10:44 AM on March 10, 2009

I like that the first hit for 1,2,3 isn't the natural numbers, it's the Fibonnacci ones. Oh and 2,4,6,8 isn't "who do we appreciate" it's the difference between consecutive primes. These are my kind of nerds.

posted by DU at 10:44 AM on March 10, 2009

posted by DU at 10:44 AM on March 10, 2009

vacapinta: "

No, why would I do that? JEEZ.

posted by Plutor at 10:47 AM on March 10, 2009

*Plutor. Did you click on the 'Previously' link?*"No, why would I do that? JEEZ.

posted by Plutor at 10:47 AM on March 10, 2009

Cool. I searched for my birthday and it turned up something... abstract.

posted by lubujackson at 10:54 AM on March 10, 2009

posted by lubujackson at 10:54 AM on March 10, 2009

I searched for 16382,79841, but it didn't come up with anything. Guess there's no predicting when this will be posted a third time.

posted by grouse at 10:55 AM on March 10, 2009 [9 favorites]

posted by grouse at 10:55 AM on March 10, 2009 [9 favorites]

36, 24, 36 is less fun than I'd hoped.

Live and learn.

posted by rokusan at 10:58 AM on March 10, 2009 [2 favorites]

Live and learn.

posted by rokusan at 10:58 AM on March 10, 2009 [2 favorites]

How are they searching this? Oh, the sequences aren't complete (which now that I think about it...duh). It's only a few megs, which I guess you can almost brute force for each query.

posted by DU at 11:00 AM on March 10, 2009

posted by DU at 11:00 AM on March 10, 2009

4, 8, 15, 16, 23, 42 is there, and that's all that matters.

posted by jeremy b at 11:02 AM on March 10, 2009

posted by jeremy b at 11:02 AM on March 10, 2009

I just like the fact that I got results for '5,5,5,5'. But I did not get n

posted by delmoi at 11:20 AM on March 10, 2009

^{0}+ 5, which seems like the most obvious one.posted by delmoi at 11:20 AM on March 10, 2009

That's because n

posted by DevilsAdvocate at 11:45 AM on March 10, 2009 [5 favorites]

^{0}+5 is 6,6,6,6...posted by DevilsAdvocate at 11:45 AM on March 10, 2009 [5 favorites]

Believe it or not, I've used this.

posted by MarshallPoe at 12:48 PM on March 10, 2009

posted by MarshallPoe at 12:48 PM on March 10, 2009

Conway's "look and say" sequence is an eternal charmer.

posted by escabeche at 2:37 PM on March 10, 2009 [1 favorite]

posted by escabeche at 2:37 PM on March 10, 2009 [1 favorite]

a(n) = (1/40)(-9n^5 + 125n^4 - 585n^3 + 1075n^2 - 446n + 160) for n = 0,1,2,3,4,5. The sequence continues 46,-52,-426,-1364,-3295...

posted by erniepan at 4:58 PM on March 10, 2009

posted by erniepan at 4:58 PM on March 10, 2009

I got the book version of this out from inter-library loan when I was a kid.

Don't know what I was thinking there.

posted by smackfu at 6:11 PM on March 10, 2009

Don't know what I was thinking there.

posted by smackfu at 6:11 PM on March 10, 2009

A book of interesting numbers? It must be impossibly big!

Consider the set of positive integers that are

posted by parudox at 10:01 PM on March 10, 2009 [1 favorite]

Consider the set of positive integers that are

*not*interesting. Suppose there's at least one; then there's a smallest one,*n*. But then*n*is the smallest positive integer that is not interesting, and surely that is quite curious! We conclude that*n*could not have been in our set, which is a contradiction. Therefore the set must have been empty, and hence all positive integers are interesting.posted by parudox at 10:01 PM on March 10, 2009 [1 favorite]

I guess it was this one: The Encyclopedia of Integer Sequences

Which is just a perfect example of something you would never use a book for now.

posted by smackfu at 6:41 AM on March 11, 2009

Which is just a perfect example of something you would never use a book for now.

posted by smackfu at 6:41 AM on March 11, 2009

So, we have three sets:

1) Interesting

2) Not Interesting

3) Interesting only by virtue of their non-Interestingness (set contains only one number)

Is the lowest member of Set 2 Interesting? No. If it was we would have to move it to Set 3. And then we'd realize: Who cares about the 2nd most interesting number because of its non-interestingness?? So we leave it as part of Set 2.

QED

posted by vacapinta at 6:50 AM on March 11, 2009

1) Interesting

2) Not Interesting

3) Interesting only by virtue of their non-Interestingness (set contains only one number)

Is the lowest member of Set 2 Interesting? No. If it was we would have to move it to Set 3. And then we'd realize: Who cares about the 2nd most interesting number because of its non-interestingness?? So we leave it as part of Set 2.

QED

posted by vacapinta at 6:50 AM on March 11, 2009

Plugging in the LOST numbers:

4 8 15 16 23 42

Returns:

a(n) is the smallest number such that twice the number of divisors of (a(n)-n)/3 gives the n-th term in the first differences of the sequence produced by the Flavius-Josephus sieve,

posted by daHIFI at 9:07 AM on March 11, 2009

4 8 15 16 23 42

Returns:

a(n) is the smallest number such that twice the number of divisors of (a(n)-n)/3 gives the n-th term in the first differences of the sequence produced by the Flavius-Josephus sieve,

posted by daHIFI at 9:07 AM on March 11, 2009

I'm a bad person for wasting bandwidth, but my user number (22022) just keeps getting cooler. Not only is it a palindrome in base 10, it's also palindromic in base 3 and base 6. It has 5 prime factors and the sum of those factors is also palindromic.

It's also a "cyclops number" - what on earth is that? Google fails to enlighten. Anybody?

posted by Quietgal at 10:06 PM on March 11, 2009

It's also a "cyclops number" - what on earth is that? Google fails to enlighten. Anybody?

posted by Quietgal at 10:06 PM on March 11, 2009

*It's also a "cyclops number" - what on earth is that? Google fails to enlighten.*

Fourth Google hit for ["cyclops number"], which just happens to be part of the site this host is about.

posted by grouse at 10:12 PM on March 11, 2009

I would have guessed the cyclops numbers would have been:

1, 2, 3, 4, 5, 6, 7, 8, 9, 10

COMMENT: Cyclops(n) is the number of eyes that n Cyclopes have.

posted by Plutor at 6:50 AM on March 12, 2009

1, 2, 3, 4, 5, 6, 7, 8, 9, 10

COMMENT: Cyclops(n) is the number of eyes that n Cyclopes have.

posted by Plutor at 6:50 AM on March 12, 2009

OK, grouse, what secret Google cabal are you in? The Google

But anyway, I'm a palindromic cyclops number -

posted by Quietgal at 3:29 PM on March 12, 2009

*I'm*allowed to use knows nothing about that page.But anyway, I'm a palindromic cyclops number -

*how cool is that?*Think I could sell my user number on eBay?posted by Quietgal at 3:29 PM on March 12, 2009

You put "cyclops number" in quotation marks, right? I just logged out to check that it wasn't a SearchWiki issue.

posted by grouse at 4:52 PM on March 12, 2009

posted by grouse at 4:52 PM on March 12, 2009

Hmm, now it shows up. Well, of course - now that grouse has blown his cover, the cabal has to do damage control.

(Actually, I saw that exact search result last night, but my brain couldn't parse the definition written in rather odd English. I was expecting something more profound than "a number with a zero in the middle". What's the big deal here? What's so special about numbers with a zero in the middle? What kind of snowflake am I?)

posted by Quietgal at 9:13 PM on March 12, 2009

(Actually, I saw that exact search result last night, but my brain couldn't parse the definition written in rather odd English. I was expecting something more profound than "a number with a zero in the middle". What's the big deal here? What's so special about numbers with a zero in the middle? What kind of snowflake am I?)

posted by Quietgal at 9:13 PM on March 12, 2009

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Really?For shame, MetaFilter. For shame.

posted by Plutor at 10:40 AM on March 10, 2009