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 A232354 Numbers k that divide sigma(k^2) where sigma is the sum of divisors function (A000203). 4
 1, 39, 793, 2379, 7137, 13167, 76921, 78507, 230763, 238887, 549549, 692289, 863577, 1491633, 1672209, 2076867, 4317885, 7615179, 8329831, 10441431, 23402223, 24989493, 37776123, 53306253, 53695813, 55871145, 74968479, 83766969, 133854435, 144688401, 161087439, 189437391 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS Squarefree terms are: 1, 39, 793, 2379, 76921, 230763, 8329831, 24989493, 53695813, 161087439, ... Quotients are: 1, 61, 873, 3783, 11737, 26543, 85563, 141911, 370773, 417263, 1155561, ... - Michel Marcus, Nov 23 2013 Many terms are also in sequence A069520, cf. A232067 for the intersection of these two sequences. - M. F. Hasler, Nov 24 2013 LINKS Donovan Johnson, Table of n, a(n) for n = 1..200 FORMULA A065764(a(n)) mod a(n) = 0. MATHEMATICA Select[Range[10^5], Divisible[DivisorSigma[1, #^2], #] &] (* Alonso del Arte, Dec 06 2013 *) PROG (PARI) isok(n) = (sigma(n^2) % n) == 0; \\ Michel Marcus, Nov 23 2013 CROSSREFS Cf. A000203, A007691, A065764, A069520, A227302, A232067, A232703, A232704. Sequence in context: A221358 A194133 A069520 * A232067 A247222 A268983 Adjacent sequences:  A232351 A232352 A232353 * A232355 A232356 A232357 KEYWORD nonn AUTHOR Alex Ratushnyak, Nov 22 2013 STATUS approved

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Last modified September 26 06:16 EDT 2021. Contains 347664 sequences. (Running on oeis4.)