A241403 - OEIS

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A241403

Numbers n such that (n^2 + 2)/3 is not prime.

0, 1, 3, 4, 5, 6, 8, 9, 10, 12, 13, 14, 15, 16, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 30, 31, 32, 33, 34, 36, 38, 39, 40, 41, 42, 44, 45, 46, 47, 48, 49, 50, 51, 52, 54, 56, 57, 58, 59, 60, 61, 62, 63, 64, 66, 67, 68, 69, 70, 71, 72, 74, 75, 76, 77, 78, 80, 81, 82, 84

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,3

LINKS

Vincenzo Librandi, Table of n, a(n) for n = 1..9000

EXAMPLE

4 is in the sequence because (4^2+2)/3 = 2*3.

MATHEMATICA

Select[Range[0, 200], ! PrimeQ[(#^2 + 2)/3] &]

PROG

(Magma) [0, 1, 3] cat [ n: n in [2..90] | not IsPrime((n^2+2) div 3) ];

CROSSREFS