A177462 Smallest k such that A000125(n)+k and A000125(n)-k are both prime.

1, 3, 2, 3, 1, 3, 4, 21, 3, 9, 18, 5, 9, 55, 36, 5, 21, 57, 30, 9, 7, 21, 14, 33, 49, 3, 150, 39, 117, 19, 12, 11, 27, 17, 66, 27, 21, 87, 10, 75, 7, 21, 14, 33, 39, 45, 30, 47, 3, 5, 210, 49, 27, 3, 30, 63, 5, 21, 58, 69, 5, 9, 168, 153, 9, 37, 204, 23, 33, 41, 78, 21, 123, 3, 100

Offset

2,2

Links

Table of n, a(n) for n=2..76.

Example

4+-1->primes. 8+-3->primes. 15+-2->primes. 26+-3->primes,..

Mathematica

g[n_]:=(n+1)*(n^2-n+6)/6; f[n_]:=Block[{k}, If[OddQ[n], k=2, k=1]; While[ !PrimeQ[n-k]||!PrimeQ[n+k], k+=2]; k]; Table[f[g[n]], {n, 2, 5!}]

Crossrefs

Cf. A000125, A078611, A172989, A172990, A177460, A177461

Sequence in context: A345440 A283976 A046818 * A106584 A213940 A236027

Adjacent sequences: A177459 A177460 A177461 * A177463 A177464 A177465

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