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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
OFFSET
1,6
LINKS
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
KEYWORD
nonn
AUTHOR
Seiichi Manyama, Jun 27 2023
STATUS
approved