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 A363899 Expansion of Sum_{k>0} k * x^(3*k) / (1 - x^(5*k)). 5
 0, 0, 1, 0, 0, 2, 0, 1, 3, 0, 0, 4, 1, 0, 5, 2, 0, 7, 0, 0, 7, 0, 1, 11, 0, 2, 9, 1, 0, 10, 0, 4, 12, 0, 0, 14, 0, 1, 16, 5, 0, 14, 1, 0, 15, 2, 0, 23, 0, 0, 17, 4, 1, 21, 0, 9, 19, 1, 0, 20, 0, 0, 22, 8, 5, 24, 0, 1, 26, 0, 0, 37, 1, 0, 25, 2, 0, 33, 0, 10, 27, 0, 1, 31, 0, 2, 29, 12, 0 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,6 LINKS Seiichi Manyama, Table of n, a(n) for n = 1..10000 FORMULA a(n) = Sum_{d|n, n/d==3 mod 5} d. G.f.: Sum_{k>0} x^(5*k-2) / (1 - x^(5*k-2))^2. MATHEMATICA a[n_] := DivisorSum[n, # &, Mod[n/#, 5] == 3 &]; Array[a, 100] (* Amiram Eldar, Jun 27 2023 *) PROG (PARI) a(n) = sumdiv(n, d, (n/d%5==3)*d); CROSSREFS Cf. A363897, A363898, A363900. Cf. A001878, A284281. Sequence in context: A154312 A236076 A364021 * A119900 A328376 A141097 Adjacent sequences: A363896 A363897 A363898 * A363900 A363901 A363902 KEYWORD nonn AUTHOR Seiichi Manyama, Jun 27 2023 STATUS approved

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Last modified September 11 21:10 EDT 2024. Contains 375839 sequences. (Running on oeis4.)