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

1,1

Comments

A subsequence of the odd squares A016754.

Links

Table of n, a(n) for n=1..42.

Maple

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

Prog

(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

Crossrefs

Cf. A327987, A327988, A016754.

Sequence in context: A196350 A196353 A166103 * A192618 A225106 A110970

Adjacent sequences: A327986 A327987 A327988 * A327990 A327991 A327992

Keyword

nonn

Author

Peter Luschny, Oct 11 2019

Status

approved