A156657 Numbers that are not safe primes.

0, 1, 2, 3, 4, 6, 8, 9, 10, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77

Offset: 1

Author

Reinhard Zumkeller, Feb 13 2009

Keywords

• nonn

Comments

A156659(a(n)) = 0; complement of A005385; A059456 is a subsequence;

A010051(a(n))*A010051((a(n)-1)/2) = 0.