A192992 Odd n > 1 such that n+1 is a semiprime times a power of two.

7, 11, 15, 17, 19, 23, 27, 29, 31, 35, 39, 41, 43, 47, 49, 51, 55, 59, 63, 65, 67, 69, 71, 75, 77, 79, 83, 87, 91, 95, 97, 99, 101, 103, 109, 111, 113, 115, 119, 123, 127, 129, 131, 135, 137, 139, 143, 147, 151, 153, 155, 159, 163, 167, 169, 171, 173, 175

Offset

1,1

Comments

Odd n such that n+1 is in A192991.

This is to thin numbers A192868 as semiprimes A001358 are to primes A000040.

Links

Table of n, a(n) for n=1..58.

Formula

a(n) = A192991(n) - 1.

Example

239 is in the sequence because 239+1 = 240 = 6th semiprime * 2^4 = 3 * 5 * 16.

Crossrefs

Cf. A005408, A001358, A192868, A192991.

Sequence in context: A053217 A144931 A166257 * A335652 A176852 A248630

Adjacent sequences: A192989 A192990 A192991 * A192993 A192994 A192995

Keyword

nonn,easy

Author

Jonathan Vos Post, Jul 13 2011

Status

approved