%I #27 Jul 31 2017 03:30:16
%S 1,6,8,12,14,15,20,21,24,27,33,38,50,54,57,62,66,69,75,77,78,80,90,99,
%T 105,110,111,117,119,138,141,143,147,150,153,155,161,162,164,168,176,
%U 188,189,192,194,203,206,209,215,218,231,236,245,246,266,272,278
%N Nonprime numbers n such that n^2 + n + 1 is prime.
%C All these numbers are in A002384 but not in A053182.
%C The generated prime numbers n^2 + n + 1 are in A185632.
%C All the generated numbers n^2 + n + 1 = 111_n are by definition Brazilian numbers: A125134. See Links: "Les nombres brésiliens" - Section V.5 page 35.
%H Michael De Vlieger, <a href="/A182253/b182253.txt">Table of n, a(n) for n = 1..10000</a>
%H Bernard Schott, <a href="/A125134/a125134.pdf">Les nombres brésiliens</a>, Quadrature, no. 76, avril-juin 2010, pages 30-38; included here with permission from the editors of Quadrature.
%t Select[Range@ 280, And[! PrimeQ@ #, PrimeQ[#^2 + # + 1]] &] (* _Michael De Vlieger_, Jul 30 2017 *)
%o (PARI) isok(n) = ! isprime(n) && isprime(n^2 + n + 1); \\ _Michel Marcus_, Sep 04 2013
%Y Cf. A002383, A002384, A053182, A053183, A085104, A125134, A185632.
%K nonn
%O 1,2
%A _Bernard Schott_, Dec 18 2012