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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 November 22 00:32 EST 2019. Contains 329383 sequences. (Running on oeis4.)