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 A007634 Numbers n such that n^2 + n + 41 is composite. (Formerly M5269) 27
 40, 41, 44, 49, 56, 65, 76, 81, 82, 84, 87, 89, 91, 96, 102, 104, 109, 117, 121, 122, 123, 126, 127, 130, 136, 138, 140, 143, 147, 155, 159, 161, 162, 163, 164, 170, 172, 173, 178, 184, 185, 186, 187, 190, 201, 204, 205, 207, 208, 209, 213, 215, 216, 217 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS A subset of this sequence is shown in A055390. - Matt C. Anderson, Jan 05 2014 If prime p divides m^2+m+41, then m+p*k is in the sequence for all k >= 1. - Robert Israel, Nov 24 2017 REFERENCES N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence). LINKS Vincenzo Librandi, Table of n, a(n) for n = 1..2000 FORMULA a(n) ~ n. - Charles R Greathouse IV, Apr 25 2014 MAPLE remove(n -> isprime(n^2+n+41), [\$1..1000]); # Robert Israel, Nov 24 2017 MATHEMATICA Select[Range[220], !PrimeQ[#^2 + # + 41] &] (* Vincenzo Librandi, Sep 28 2012 *) PROG (MAGMA) [n: n in [0..220] | not IsPrime(n^2 + n + 41)]; // Vincenzo Librandi, Sep 28 2012 (PARI) is(n)=!isprime(n^2+n+41) \\ Charles R Greathouse IV, Apr 25 2014 CROSSREFS Cf. A002837, A055390, A201998. Sequence in context: A273770 A165861 A082763 * A228184 A128843 A214563 Adjacent sequences:  A007631 A007632 A007633 * A007635 A007636 A007637 KEYWORD nonn,easy AUTHOR STATUS approved

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Last modified October 14 07:00 EDT 2019. Contains 327995 sequences. (Running on oeis4.)