A138887 Numbers that are not Sophie Germain primes.

0, 1, 4, 6, 7, 8, 9, 10, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 24, 25, 26, 27, 28, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75

Offset

0,3

Comments

Nonnegative integers that are not in A005384.

A156660(a(n)) = 0; A053176 is a subsequence. - Reinhard Zumkeller, Feb 18 2009

Links

Table of n, a(n) for n=0..67.

Mathematica

Select[Range[0, 80], !PrimeQ[#] || ! PrimeQ[2#+1] &] (* Stefano Spezia, Feb 01 2026 *)

Crossrefs

Cf. A001690, A005384, A053176, A062289, A138888, A138889, A138890, A138891.

Sequence in context: A074764 A381767 A101087 * A216845 A031949 A043693

Adjacent sequences: A138884 A138885 A138886 * A138888 A138889 A138890

Keyword

easy,nonn

Author

Omar E. Pol, Apr 05 2008

Extensions

a(61)-a(67) from Stefano Spezia, Feb 01 2026

Status

approved