A168080 Numbers n such that exactly two of n+-1, n+-2 and n+-3 are primes.

0, 1, 2, 3, 9, 12, 15, 18, 21, 22, 26, 28, 30, 32, 34, 38, 39, 42, 45, 46, 50, 56, 58, 60, 62, 64, 68, 69, 72, 74, 76, 80, 81, 82, 86, 98, 99, 102, 105, 108, 111, 112, 128, 129, 130, 134, 136, 138, 140, 148, 150, 152, 154, 160, 164, 165, 166, 170, 176, 178, 180, 182

Offset: 1

Author

Juri-Stepan Gerasimov, Nov 18 2009

Keywords

• nonn

Links

• G. C. Greubel, Table of n, a(n) for n = 1..1000

Crossrefs

Cf. A000040, A100317.

Programs

Mathematica

okQ[n_]:=Length[Select[Drop[Range[n-3,n+3],{4}],PrimeQ]]==2; Join[{0,1}, Select[Range[0,200],okQ]] (* Harvey P. Dale, Jun 29 2011 *)

Extensions

Corrected (14 removed, 58, 62, 74 inserted, etc.) by R. J. Mathar, Jun 04 2010