A070610 Number of positive integers k such that sigma(k) divides sigma(n).

1, 2, 2, 2, 3, 6, 3, 3, 2, 5, 6, 5, 3, 10, 10, 3, 5, 4, 3, 8, 5, 9, 10, 12, 3, 8, 5, 8, 5, 18, 5, 4, 13, 7, 13, 4, 2, 12, 8, 10, 8, 19, 3, 15, 6, 18, 13, 7, 3, 5, 18, 5, 7, 21, 18, 21, 7, 10, 12, 27, 4, 19, 6, 2, 15, 26, 3, 13, 19, 26, 18, 6, 2, 7, 7, 8, 19, 27, 7, 9, 2, 13, 15, 14, 13, 9

Offset

1,2

Links

Antti Karttunen, Table of n, a(n) for n = 1..16384

Index entries for sequences related to sigma(n)

Formula

a(n) = A074754(A000203(n)). - Antti Karttunen, Nov 17 2017

Prog

(PARI) for(n=1, 150, print1(sum(i=1, 10*n, if((sigma(n))%(sigma(i)), 0, 1)), ", "))
(PARI) A070610(n) = { my(s=sigma(n)); sum(k=1, s, !(s%sigma(k))); }; \\ Antti Karttunen, Nov 17 2017

Crossrefs

Cf. A000203, A070242, A071181, A074754.

Sequence in context: A268595 A299019 A347879 * A156820 A104346 A318238

Adjacent sequences: A070607 A070608 A070609 * A070611 A070612 A070613

Keyword

easy,nonn

Author

Benoit Cloitre, May 13 2002

Extensions

Offset corrected, name edited by Antti Karttunen, Nov 17 2017

Status

approved