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

%I #8 Feb 04 2016 16:26:19

%S 21557,26681,128981,2073347,3992201,4889237,6184637,11900501,21456047,

%T 24598361,33771581,34864211,50943791,55793951,56421347,61218251,

%U 67787537,69726647,76345121,86145881,90261707,92865791,99624647,102960281,108846161

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

%C The first term is A164926(8).

%H T. D. Noe, <a href="/A211236/b211236.txt">Table of n, a(n) for n = 1..1000</a>

%t 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

%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 *)

%Y Cf. A067774, A164926.

%K nonn

%O 1,1

%A _T. D. Noe_, Apr 08 2012

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Last modified December 3 19:10 EST 2023. Contains 367540 sequences. (Running on oeis4.)