A388013 Number of divisors d of n for which sigma(d)/d >= 5/3.

0, 0, 0, 1, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 3, 0, 2, 0, 3, 0, 0, 0, 5, 0, 0, 0, 3, 0, 3, 0, 4, 0, 0, 0, 5, 0, 0, 0, 5, 0, 3, 0, 2, 1, 0, 0, 7, 0, 2, 0, 2, 0, 3, 0, 5, 0, 0, 0, 7, 0, 0, 0, 5, 0, 2, 0, 2, 0, 3, 0, 8, 0, 0, 0, 2, 0, 2, 0, 7, 0, 0, 0, 7, 0, 0, 0, 4, 0, 6, 0, 2, 0, 0, 0, 9, 0, 2, 0, 5, 0, 2, 0, 4, 1, 0, 0, 7, 0, 2, 0, 7, 0, 2, 0, 2, 0, 0, 0, 11

Offset

1,8

Links

Antti Karttunen, Table of n, a(n) for n = 1..65537

Index entries for sequences related to sigma(n).

Mathematica

A388013[n_] := DivisorSum[n, 1 &, 3*DivisorSigma[1, #] >= 5*# &];
Array[A388013, 100] (* Paolo Xausa, Sep 13 2025 *)

Prog

(PARI) A388013(n) = sumdiv(n, d, ((sigma(d)/d)>=(5/3)));

Crossrefs

Cf. A000203.

Cf. A388011 (positions of 0's), A388012 (of terms > 0), A388014 (of 1's).

Sequence in context: A349906 A320439 A321252 * A225345 A335427 A083280

Adjacent sequences: A388010 A388011 A388012 * A388014 A388015 A388016

Keyword

nonn

Author

Antti Karttunen, Sep 13 2025

Status

approved