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 A133157 Numbers k such that k^2 + k - 41 is prime. 1
 8, 15, 20, 21, 26, 29, 36, 45, 48, 59, 68, 69, 75, 78, 98, 99, 108, 111, 113, 120, 129, 134, 138, 140, 143, 161, 168, 185, 188, 189, 210, 213, 215, 216, 218, 224, 230, 231, 234, 251, 255, 260, 266, 273, 278, 279, 281, 290, 294, 299, 306, 308, 314, 320, 329, 356 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS Table of n, a(n) for n=1..56. EXAMPLE If k=8, then k^2 + n - 41 = 31 (prime). If k=99, then k^2 + n - 41 = 9859 (prime). MAPLE isA133157 := proc(n) isprime(n*(n+1)-41) ; end: for n from 1 to 400 do if isA133157(n) then printf("%d, ", n) ; fi ; od: # R. J. Mathar, Jan 08 2008 MATHEMATICA Select[Range[7, 400], PrimeQ[ #^2 + # - 41] &] (* Stefan Steinerberger, Dec 24 2007 *) PROG (PARI) is(n)=isprime(n^2+n-41) \\ Charles R Greathouse IV, Jun 13 2017 CROSSREFS Cf. A002837. Sequence in context: A160524 A161541 A247081 * A014544 A237610 A122754 Adjacent sequences: A133154 A133155 A133156 * A133158 A133159 A133160 KEYWORD nonn,easy AUTHOR Parthasarathy Nambi, Dec 17 2007 EXTENSIONS More terms from Stefan Steinerberger, Dec 24 2007 More terms from R. J. Mathar, Jan 08 2008 STATUS approved

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Last modified September 24 00:14 EDT 2023. Contains 365554 sequences. (Running on oeis4.)