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 A145292 Composite numbers generated by the Euler polynomial x^2 + x + 41. 17
 1681, 1763, 2021, 2491, 3233, 4331, 5893, 6683, 6847, 7181, 7697, 8051, 8413, 9353, 10547, 10961, 12031, 13847, 14803, 15047, 15293, 16043, 16297, 17071, 18673, 19223, 19781, 20633, 21797, 24221, 25481, 26123, 26447, 26773, 27101, 29111 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS The Euler polynomial x^2 + x + 41 gives primes for consecutive x from 0 to 39. For numbers x for which x^2 + x + 41 is not prime see A007634. Let P(x)=x^2 + x + 41. In view of identity P(x+P(x))=P(x)*P(x+1), all values of P(x+P(x)) are in the sequence. - Vladimir Shevelev, Jul 16 2012 LINKS Reinhard Zumkeller, Table of n, a(n) for n = 1..10000 FORMULA a(n) ~ n^2. [Charles R Greathouse IV, Dec 08 2011] MATHEMATICA a = {}; Do[If[PrimeQ[x^2 + x + 41], null, AppendTo[a, x^2 + x + 41]], {x, 0, 500}]; a Select[Table[x^2+x+41, {x, 200}], CompositeQ] (* Requires Mathematica version 10 or later *) (* Harvey P. Dale, Dec 21 2018 *) PROG (Haskell) a145292 n = a145292_list !! (n-1) a145292_list = filter ((== 0) . a010051) a202018_list -- Reinhard Zumkeller, Dec 09 2011 (PARI) for(n=1, 1e3, if(!isprime(t=n^2+n+41), print1(t", "))) \\ Charles R Greathouse IV, Dec 08 2011 CROSSREFS Cf. A005846, A007634, A145293, A145294, A145295. Intersection of A002808 and A202018; A010051. Sequence in context: A172768 A172667 A221204 * A228183 A175897 A322745 Adjacent sequences:  A145289 A145290 A145291 * A145293 A145294 A145295 KEYWORD nonn AUTHOR Artur Jasinski, Oct 06 2008 STATUS approved

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Last modified May 30 09:24 EDT 2020. Contains 334723 sequences. (Running on oeis4.)