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 A117012 Primes of the form n^2+5n+c (n>=0), where c=3 for even n and c=-3 for odd n. 0
 3, 17, 47, 107, 173, 269, 503, 641, 809, 983, 1187, 1637, 2441, 2753, 4157, 4547, 4967, 5393, 5849, 6311, 6803, 7829, 8363, 9497, 11981, 12653, 13331, 14753, 15497, 17027, 22943, 26723, 29753, 31859, 32933, 38609, 39791, 42221, 47297, 49943, 58313 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Alternating Euler quadratic prime generating polynomial. REFERENCES Harvey Cohn, Advanced Number Theory,Dover, New York, 1962, page 155. LINKS MATHEMATICA f[n_] := If[Mod[n, 2] == 1, n^2 + 5*n - 3, n^2 + 5*n + 3] b = Flatten[Table[If[PrimeQ[f[n]] == True, f[n], {}], {n, 1, 100}]] PROG (PARI) m=250; for(n=1, m, k=n^2+5*n+3-6*(n%2); if(isprime(k), print1(k, ", "))) CROSSREFS Cf. A014209, A082605. Sequence in context: A106078 A087908 A152472 * A162291 A095697 A154304 Adjacent sequences:  A117009 A117010 A117011 * A117013 A117014 A117015 KEYWORD nonn AUTHOR Roger L. Bagula, Apr 16 2006 EXTENSIONS Edited and extended by N. J. A. Sloane, Apr 17 2006 STATUS approved

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Last modified September 17 03:42 EDT 2021. Contains 347478 sequences. (Running on oeis4.)