A327989 Nonnegative integers k such that Sum_{d|k} k & (k/d) is an odd prime, where & is the bitwise AND operator.

9, 25, 81, 121, 289, 625, 729, 841, 1681, 3249, 3481, 5041, 7225, 8281, 8649, 9025, 10201, 11449, 13689, 15129, 18769, 19881, 22201, 25281, 27225, 28561, 29241, 31329, 32041, 33489, 34225, 36481, 38025, 38809, 42849, 46225, 48841, 51529, 53361, 55225, 56169, 57121

Offset: 1

Author

Peter Luschny, Oct 11 2019

Keywords

• nonn

Comments

A subsequence of the odd squares A016754.

Crossrefs

Cf. A327987, A327988, A016754.

Programs

Magma

[k:k in [1..60000]|IsOdd(a) and IsPrime(a) where a is &+[BitwiseAnd(d,k div d):d in Divisors(k)]]; // Marius A. Burtea, Oct 11 2019

Maple

select(k -> (A327987(k) <> 2 and isprime(A327987(k))), [$0..60000]);