id:A118123 - OEIS Search Results

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Number of k's such that prime(n+1) = prime(n) + (prime(n) mod k).

+0
4

0, 0, 1, 0, 2, 1, 3, 2, 1, 3, 1, 2, 3, 2, 1, 1, 3, 2, 4, 3, 1, 4, 3, 3, 2, 5, 4, 7, 6, 2, 2, 2, 7, 2, 5, 2, 1, 2, 3, 1, 3, 3, 7, 6, 7, 2, 1, 2, 8, 7, 1, 3, 5, 4, 1, 1, 3, 2, 6, 5, 5, 3, 2, 3, 2, 2, 4, 2, 7, 6, 1, 6, 2, 1, 6, 3, 2, 2, 2, 5, 3, 2, 7, 3, 6, 3, 6, 2, 7, 6, 5, 2, 6, 5, 10, 3, 2, 3, 2, 2, 2, 3, 1, 9, 2 (list; graph; listen)

	OFFSET	`1,5`
	FORMULA	`a(n) = number k such that prime(n+1) = prime(n) + (prime(n) mod k), or 0 if no such k exists.`
	PROGRAM	`(PARI) f[n_] := If[n == 1, 0, Block[{p = Prime@n, np = Prime[n + 1]}, Length@Select[Divisors[2p - np], # >= np - p &]]]; Array[f, 105]`
	CROSSREFS	`Cf. A117078, A117563.` `Sequence in context: A126597 A076081 A107338 this_sequence A131756 A085014 A082074` `Adjacent sequences: A118120 A118121 A118122 this_sequence A118124 A118125 A118126`
	KEYWORD	`nonn`
	AUTHOR	`Remi Eismann and Robert G. Wilson v (rgwv(AT)rgwv.com), May 12 2006`

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Last modified November 18 20:14 EST 2008. Contains 147244 sequences.

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