A337378 Numbers k for which A003961(k) > 2*sigma(k).

16, 24, 27, 32, 36, 40, 45, 48, 49, 54, 56, 63, 64, 72, 80, 81, 84, 90, 96, 98, 99, 100, 104, 105, 108, 112, 117, 120, 125, 126, 128, 135, 140, 144, 147, 152, 153, 160, 162, 168, 171, 175, 176, 180, 184, 189, 192, 196, 198, 200, 207, 208, 210, 216, 224, 225, 234, 240, 243, 245, 248, 250, 252, 256, 264, 270, 272, 273

Offset: 1

Author

Antti Karttunen, Aug 27 2020

Keywords

• nonn

Comments

Note that A003961(n) >= sigma(n) for all n. See A286385.

Links

• Antti Karttunen, Table of n, a(n) for n = 1..20000
• Index entries for sequences computed from indices in prime factorization
• Index entries for sequences related to sigma(n)

Crossrefs

Subsequence of A246282 and of A337381.

Positions of negative terms in A377984, and in A378751.

Cf. A000203, A003961, A286385.

Cf. A337379 (complement), A337380 (characteristic function).

Programs

PARI

A003961(n) = { my(f = factor(n)); for (i=1, #f~, f[i, 1] = nextprime(f[i, 1]+1)); factorback(f); };
isA337378(n) = (A003961(n)>2*sigma(n));