A211236 Prime numbers p such that x^2 + x + p produces primes for x = 0..7 but not x = 8.

21557, 26681, 128981, 2073347, 3992201, 4889237, 6184637, 11900501, 21456047, 24598361, 33771581, 34864211, 50943791, 55793951, 56421347, 61218251, 67787537, 69726647, 76345121, 86145881, 90261707, 92865791, 99624647, 102960281, 108846161

Offset: 1

Author

T. D. Noe, Apr 08 2012

Keywords

• nonn

Comments

The first term is A164926(8).

Links

• T. D. Noe, Table of n, a(n) for n = 1..1000

Crossrefs

Cf. A067774, A164926.

Programs

Mathematica

lookfor = 8; t = {}; n = 0; While[Length[t] < 25, n++; c = Prime[n]; i = 1; While[PrimeQ[i^2 + i + c], i++]; If[i == lookfor, AppendTo[t, c]]]; t
Select[Prime[Range[6250000]],AllTrue[#+{2,6,12,20,30,42,56}, PrimeQ] && !PrimeQ[ #+72]&] (* The program uses the AllTrue function from Mathematica version 10 *) (* Harvey P. Dale, Feb 04 2016 *)