A104636 - OEIS

A104636

Even n such that 2n+1 is prime.

2, 6, 8, 14, 18, 20, 26, 30, 36, 44, 48, 50, 54, 56, 68, 74, 78, 86, 90, 96, 98, 114, 116, 120, 128, 134, 138, 140, 146, 156, 158, 168, 174, 176, 186, 194, 198, 200, 204, 210, 216, 224, 228, 230, 254, 260, 270, 278, 284, 288, 296, 300, 306, 308, 320, 326, 330

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OFFSET

1,1

COMMENTS

If q = 2*n + 1 is prime, and n is even, q divides (n!)^2 + 1. - Arkadiusz Wesolowski, Sep 06 2012

LINKS

T. D. Noe, Table of n, a(n) for n = 1..1000

MATHEMATICA

Select[Range[2, 300, 2], PrimeQ[2*# + 1] &]

CROSSREFS

Cf. A005097, A104635.

Sequence in context: A213374 A271729 A249624 * A212014 A270050 A137831