id:A114228 - OEIS Search Results

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Smallest number k (k>=1) that makes the n-th prime prime[n] plus 2*prime[k] a prime.

+0
7

1, 2, 1, 2, 1, 2, 1, 2, 4, 2, 1, 2, 1, 2, 2, 4, 2, 1, 6, 2, 1, 2, 4, 1, 2, 1, 2, 1, 4, 1, 2, 4, 3, 4, 2, 2, 1, 2, 2, 4, 3, 2, 1, 4, 7, 5, 1, 2, 1, 2, 8, 3, 2, 2, 2, 4, 2, 1, 6, 3, 4, 1, 2, 1, 4, 2, 3, 2, 1, 2, 4, 2, 2, 1, 2, 12, 1, 8, 3, 4, 3, 6, 2, 1, 2, 4, 1, 2, 1, 12, 11, 1, 14, 1, 2, 4, 6, 7, 2, 3, 2, 2, 8 (list; graph; listen)

	OFFSET	`2,2`
	EXAMPLE	`Prime[2]=3, 3+2Prime[1]=7 is prime, so k[2]=1;` `Prime[3]=5, 5+2Prime[2]=11 is prime, so k[3]=2;` `...` `Prime[20]=71, 71+2*Prime[6]=97 is prime, so k[20]=6`
	MATHEMATICA	`Table[p1 = Prime[n1]; n2 = 1; p2 = 2; While[ cp = p1 + 2*p2; ! PrimeQ[cp], n2++; p2 = Prime[n2]]; n2, {n1, 2, 201}]`
	CROSSREFS	`Cf. A114227.` `Sequence in context: A112632 A123738 A030738 this_sequence A060938 A119647 A087942` `Adjacent sequences: A114225 A114226 A114227 this_sequence A114229 A114230 A114231`
	KEYWORD	`easy,nonn`
	AUTHOR	`Lei Zhou (lzhou5(AT)emory.edu), Nov 18 2005`

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Last modified August 19 23:53 EDT 2008. Contains 142930 sequences.

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