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

Offset: 1

Author

Zak Seidov, Mar 18 2005

Keywords

• easy
• nonn

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

Crossrefs

Cf. A005097, A104635.

Programs

Mathematica

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

Extensions

a(48)-a(57) from Arkadiusz Wesolowski, Sep 06 2012