A068986 Numbers k such that Sum_{d|k} sigma(d)/d is an integer.

1, 21, 105, 1050, 1155, 24921, 26565, 45150, 49842, 59455, 249210, 274131, 548262, 1129645, 1151325, 1248555, 1309350, 2302650, 2741310, 3388935, 4605300, 6305013, 12610026, 13417131, 14685385, 23722545, 25750550, 26834262, 30154410, 33388425, 42997750, 44056155

Offset

1,2

Comments

Also numbers k that divide A060640(k). - Seiichi Manyama, May 08 2021

Links

Michel Marcus, Table of n, a(n) for n = 1..64

Prog

(PARI) for(n=1, 10^7, if(frac(sumdiv(n, d, sigma(d)/d))==0, print1(n, ", ")))

Crossrefs

Cf. A000203, A060640, A017665, A017666.

Sequence in context: A116689 A235876 A279763 * A219631 A226742 A077400

Adjacent sequences: A068983 A068984 A068985 * A068987 A068988 A068989

Keyword

nonn

Author

Benoit Cloitre, Apr 06 2002

Extensions

More terms from Jason Earls, Apr 09 2002

a(22)-a(25) from Jinyuan Wang, Apr 06 2020

a(26)-a(32) from Michel Marcus, Apr 06 2020

Status

approved