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 A241267 Numbers n such that 4*n^2 + 4*n + 653 is not prime. 1
 18, 19, 21, 24, 28, 33, 39, 46, 54, 60, 61, 62, 63, 65, 67, 72, 73, 75, 81, 82, 84, 85, 86, 93, 95, 96, 100, 101, 103, 104, 105, 109, 110, 111, 112, 117, 121, 122, 123, 125, 130, 137, 138, 139, 141, 142, 143, 144, 147, 152, 153, 154, 159, 160, 161, 165, 166 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS Vincenzo Librandi, Table of n, a(n) for n = 1..1000 EXAMPLE 19 is in this sequence because 4*19^2 + 4*19 + 653 = 2173 = 41*53. MATHEMATICA Select[Range[0, 250], ! PrimeQ[4 #^2 + 4 # + 653] &] PROG (MAGMA) [n: n in [0..250] | not IsPrime(4*n^2+4*n+653)]; CROSSREFS Complement of A188459. Sequence in context: A018823 A025144 A326540 * A241848 A146331 A308894 Adjacent sequences:  A241264 A241265 A241266 * A241268 A241269 A241270 KEYWORD nonn,easy AUTHOR Vincenzo Librandi, Apr 20 2014 STATUS approved

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Last modified December 9 05:44 EST 2021. Contains 349627 sequences. (Running on oeis4.)