

A226922


Values of n such that L(2) and N(2) are both prime, where L(k) = (n^2+n+1)*2^(2*k) + (2*n+1)*2^k + 1, N(k) = (n^2+n+1)*2^k + n.


1



1, 1, 11, 31, 55, 115, 191, 221, 271, 361, 515, 601, 641, 695, 745, 1061, 1075, 1201, 1259, 1399, 1495, 1651, 1669, 1915, 2381, 2449, 2921, 2959, 2969, 2971, 3035, 3049, 3215, 3265, 3419, 3611, 3709, 3889, 4045, 4229, 4241, 4301, 4561, 4565, 4589, 4721, 4849, 4931, 5039, 5081, 5555, 5795, 5821, 5879, 5921
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OFFSET

1,3


COMMENTS

Computed with PARI using commands similar to those used to compute A226921.


LINKS



MATHEMATICA

k = 2; (* adjust for related sequences *) fL[n_] := (n^2 + n + 1)*2^(2*k) + (2*n + 1)*2^k + 1; fN[n_] := (n^2 + n + 1)*2^k + n; nn = 6000; A = {}; For[n = nn, n <= nn, n++, If[PrimeQ[fL[n]] && PrimeQ[fN[n]], AppendTo[A, n]]]; cmpfunc[x_, y_] := If[x == y, Return[True], ax = Abs[x]; ay = Abs[y]; If[ax == ay, Return[x < y], Return[ ax < ay]]]; Sort[A, cmpfunc] (* JeanFrançois Alcover, Jul 17 2013, translated and adapted from Joerg Arndt's Pari program in A226921 *)


CROSSREFS



KEYWORD

sign


AUTHOR



EXTENSIONS



STATUS

approved



