A326133 Numbers n for which sigma(n) > A005187(n).

6, 12, 18, 20, 24, 28, 30, 36, 40, 42, 48, 54, 56, 60, 66, 70, 72, 78, 80, 84, 88, 90, 96, 100, 102, 104, 108, 110, 112, 114, 120, 126, 132, 138, 140, 144, 150, 156, 160, 162, 168, 174, 176, 180, 186, 192, 196, 198, 200, 204, 208, 210, 216, 220, 222, 224, 228, 234, 240, 246, 252, 258, 260, 264, 270, 272, 276, 280, 282, 288, 294, 300

Offset: 1

Author

Antti Karttunen, Jun 11 2019

Keywords

• nonn

Comments

Differs from A023196 for the first time at the 28th term, which here is 110, which is not included in A023196.

Note that as there is at least one odd number (815634435) in A326138, it means that A005231 does not contain all odd terms of this sequence.

Links

• Antti Karttunen, Table of n, a(n) for n = 1..16260
• Index entries for sequences related to binary expansion of n.
• Index entries for sequences related to sigma(n).
• Index entries for sequences where any odd perfect numbers must occur.

Crossrefs

Positions of negative terms in A294898.

Cf. A000203, A005187, A023196.

Cf. A000396, A005231, A083207, A111592, A326131, A326138 (subsequences).

Programs

Mathematica

Select[Range[300], DivisorSigma[1, #] > 2*# - DigitCount[2*#, 2, 1] &] (* Amiram Eldar, Aug 06 2023 *)

PARI

A005187(n) = { my(s=n); while(n>>=1, s+=n); s; };
isA326133(n) = (sigma(n)>A005187(n));