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

Author

Vladimir Joseph Stephan Orlovsky, May 09 2010

Keywords

• nonn

Examples

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

Crossrefs

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

Programs

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!}]

Extensions

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