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%I M5269 #47 Jul 26 2023 09:14:38
%S 40,41,44,49,56,65,76,81,82,84,87,89,91,96,102,104,109,117,121,122,
%T 123,126,127,130,136,138,140,143,147,155,159,161,162,163,164,170,172,
%U 173,178,184,185,186,187,190,201,204,205,207,208,209,213,215,216,217
%N Numbers k such that k^2 + k + 41 is composite.
%C A subset of this sequence is shown in A055390. - _Matt C. Anderson_, Jan 05 2014
%C If prime p divides m^2+m+41, then m+p*j is in the sequence for all j >= 1. - _Robert Israel_, Nov 24 2017
%C Euler noted that the first 40 values of this polynomial, starting with k=0, are all primes. - _Harvey P. Dale_, Jul 25 2023
%D N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
%H Vincenzo Librandi, <a href="/A007634/b007634.txt">Table of n, a(n) for n = 1..2000</a>
%F a(n) ~ n. - _Charles R Greathouse IV_, Apr 25 2014
%p remove(n -> isprime(n^2+n+41), [$1..1000]); # _Robert Israel_, Nov 24 2017
%t Select[Range[220], !PrimeQ[#^2 + # + 41] &] (* _Vincenzo Librandi_, Sep 28 2012 *)
%o (Magma) [n: n in [0..220] | not IsPrime(n^2 + n + 41)]; // _Vincenzo Librandi_, Sep 28 2012
%o (PARI) is(n)=!isprime(n^2+n+41) \\ _Charles R Greathouse IV_, Apr 25 2014
%Y Cf. A002837, A055390, A201998.
%K nonn,easy
%O 1,1
%A _N. J. A. Sloane_, _Mira Bernstein_, _Robert G. Wilson v_
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