A324659 a(n) = (1/2)*A318468(n), where A318468(n) is bitwise-AND of 2*n and sigma(n).

0, 0, 2, 0, 1, 6, 4, 0, 0, 8, 2, 12, 5, 12, 12, 0, 1, 18, 2, 20, 16, 18, 4, 24, 9, 16, 16, 28, 13, 4, 16, 0, 0, 2, 0, 36, 1, 6, 4, 40, 1, 32, 2, 40, 37, 36, 8, 48, 16, 34, 32, 48, 17, 52, 36, 56, 40, 40, 26, 20, 29, 48, 52, 0, 0, 64, 2, 4, 0, 64, 4, 64, 1, 8, 10, 68, 0, 68, 8, 80, 16, 18, 2, 80, 20, 66, 20, 88, 9, 80

Offset: 1

Author

Antti Karttunen, Mar 14 2019

Keywords

• nonn
• look

Links

• Antti Karttunen, Table of n, a(n) for n = 1..16384
• Index entries for sequences related to binary expansion of n
• Index entries for sequences related to sigma(n)

Crossrefs

Cf. A000203, A004198, A318458, A318468, A324648, A324658.

Cf. A324652 (fixed points).

Programs

Mathematica

Array[BitAnd[2*#, DivisorSigma[1, #]]/2 &, 100] (* Paolo Xausa, Mar 11 2024 *)

PARI

A324659(n) = (bitand(2*n,sigma(n))/2);

Formula

a(n) = A318468(n)/2.

a(n) = n - A324658(n).