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A177460 Smallest k such that A000217(n)+k and A000217(n)-k are both prime. 1
0, 1, 3, 2, 2, 9, 5, 2, 12, 5, 5, 12, 2, 7, 27, 4, 8, 9, 13, 2, 24, 5, 7, 12, 2, 5, 27, 4, 2, 75, 19, 38, 18, 11, 7, 30, 2, 7, 9, 2, 16, 63, 7, 4, 12, 25, 5, 12, 16, 35, 51, 2, 2, 9, 13, 16, 12, 17, 41, 60, 20, 13, 51, 8, 32, 9, 5, 22, 18, 35, 19, 12, 22, 7, 75, 34, 2, 93, 11, 2, 30, 25, 11 (list; graph; refs; listen; history; text; internal format)
OFFSET

2,3

LINKS

Table of n, a(n) for n=2..84.

EXAMPLE

3+-0->primes. 6+-1->primes. 10+-3->primes. 15+-2->primes,..

MATHEMATICA

f[n_]:=Block[{k}, If[OddQ[n], k=0, k=1]; While[ !PrimeQ[n-k]||!PrimeQ[n+k], k+=2]; k]; Table[f[n*(n+1)/2], {n, 2, 5!}]

CROSSREFS

Cf. A000217, A172989, A172990

Sequence in context: A195422 A176530 A011319 * A091015 A256097 A058147

Adjacent sequences:  A177457 A177458 A177459 * A177461 A177462 A177463

KEYWORD

nonn

AUTHOR

Vladimir Joseph Stephan Orlovsky, May 09 2010

EXTENSIONS

Definition rephrased and offset adapted by R. J. Mathar, Aug 15 2010

STATUS

approved

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Last modified October 16 18:56 EDT 2019. Contains 328102 sequences. (Running on oeis4.)