A332446 Numbers k for which A087808(sigma(k)) is equal to A087808(2*k).

3, 6, 11, 19, 28, 43, 59, 67, 83, 107, 131, 139, 163, 179, 211, 216, 227, 251, 267, 283, 286, 307, 331, 347, 379, 419, 443, 467, 491, 496, 499, 523, 547, 563, 571, 587, 598, 619, 643, 659, 683, 691, 726, 739, 787, 811, 827, 859, 883, 907, 947, 971, 1019, 1051, 1091, 1123, 1163, 1171, 1187, 1259, 1283, 1291, 1307, 1427, 1451

Offset: 1

Author

Antti Karttunen, Feb 14 2020

Keywords

• nonn

Comments

Conjecture: includes all terms of A007520. - Bill McEachen, Dec 10 2023

Links

• Antti Karttunen, Table of n, a(n) for n = 1..20751
• Index entries for sequences related to binary expansion of n
• Index entries for sequences related to sigma(n)

Crossrefs

Cf. A000203, A007520, A087808.

Subsequences: A000396, A332445.

Cf. A331751, A331752, A332208 for similar sequences.

Programs

PARI

A087808(n) = if(n<1, 0, if(n%2==0, 2*A087808(n/2), A087808((n-1)/2)+1));
isA332446(n) = (A087808(2*n)==A087808(sigma(n)));