login

Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).

A055715
Numbers k such that k | sigma_11(k).
2
1, 6, 28, 120, 402, 496, 644, 672, 920, 1366, 1608, 1932, 2680, 2760, 3417, 3966, 4098, 4623, 4975, 5152, 6210, 6834, 8040, 8128, 8280, 9246, 9528, 9950, 12294, 13668, 15008, 15456, 15864, 16392, 18492, 19900, 24120, 24840, 25954, 27320, 27336, 29850, 30240, 32760
OFFSET
1,2
COMMENTS
sigma_11(k) is the sum of the 11th powers of the divisors of k (A013959).
LINKS
MATHEMATICA
Do[If[Mod[DivisorSigma[11, n], n]==0, Print[n]], {n, 1, 40000}]
PROG
(PARI) isok(k) = (sigma(k, 11) % k) == 0; \\ Michel Marcus, Nov 09 2019
KEYWORD
nonn
AUTHOR
Robert G. Wilson v, Jun 09 2000
EXTENSIONS
a(37)-a(40) corrected and more terms added by Amiram Eldar, Nov 09 2019
STATUS
approved