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A007636 Numbers k such that k^2 + k + 17 is composite.
(Formerly M4996)
2
16, 17, 20, 25, 32, 33, 34, 36, 39, 41, 43, 48, 50, 51, 52, 54, 55, 58, 61, 65, 66, 67, 68, 69, 71, 74, 77, 78, 80, 83, 84, 85, 88, 89, 90, 93, 94, 96, 97, 99, 100, 101, 102, 105, 106, 107, 111, 112, 115, 116, 117, 118, 119, 122, 124, 126, 131, 134, 135, 136, 137 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Complement of A028823. - Michel Marcus, Jun 17 2013

REFERENCES

N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

LINKS

Vincenzo Librandi, Table of n, a(n) for n = 1..3500

MATHEMATICA

Select[Range[200], !PrimeQ[#^2 + # + 17] &] (* Vincenzo Librandi, Jun 08 2017 *)

PROG

(MAGMA) [n: n in [0..200]| not IsPrime(n^2+n+17)]; // Vincenzo Librandi, Jun 08 2017

CROSSREFS

Sequence in context: A138599 A258265 A261344 * A241751 A244431 A151977

Adjacent sequences:  A007633 A007634 A007635 * A007637 A007638 A007639

KEYWORD

nonn,easy

AUTHOR

N. J. A. Sloane, Mira Bernstein, Robert G. Wilson v

STATUS

approved

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Last modified April 17 02:26 EDT 2021. Contains 343059 sequences. (Running on oeis4.)