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5 posts tagged with sequences.

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## a(n)=a(n−1)+gcd(n,a(n−1)).

Go ahead: Press the button.

*A number is printed on the tape. Press again and another number appears. Keep going. A few more. Notice anything special about those numbers? The sequence begins: 5, 3, 11, 3, 23, 3, 47, 3, 5, 3, 101, 3, 7, 11, 3, 13, 233, 3, 467, 3, 5, 3, . . .*## Significand of the figure

From the somewhat arbitrary and dimensionful to the timeless classic, one man's subjective list of notable properties of specific numbers. [more inside]

## The On-Line Encyclopedia of Integer Sequences

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

## 3 is an odd prime, 5 is an odd prime, 7 is an odd prime, 9 is a very odd prime...

The Prime Game is not really much of a game, but it

*is*a neat & little-known fact about the decimal representation of prime numbers.## Can you stump the Encyclopedia of Integer Sequences?

Can you stump the Encyclopedia of Integer Sequences? Every identifiable sequence known to man, including:

If your sequence does not appear there, you might want to try the Super Seeker.

*Name: Busy Beaver problem: maximal number of steps that an n-state Turing machine can make on an initially blank tape before eventually halting.*

Comment: The sequence grows faster than any computable function of n, and so is non-computable.

Keywords: hard,huge,nice,nonn,brefComment: The sequence grows faster than any computable function of n, and so is non-computable.

Keywords: hard,huge,nice,nonn,bref

If your sequence does not appear there, you might want to try the Super Seeker.

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