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A364097
Expansion of Sum_{k>0} k * x^(3*k-2) / (1 - x^(5*k-4)).
1
1, 1, 1, 3, 1, 1, 4, 1, 1, 7, 1, 1, 6, 1, 1, 9, 1, 4, 8, 1, 1, 11, 1, 1, 10, 5, 1, 13, 4, 1, 12, 1, 1, 20, 1, 1, 14, 1, 1, 20, 1, 11, 16, 1, 1, 19, 1, 1, 18, 8, 4, 21, 1, 1, 25, 1, 1, 35, 1, 1, 22, 4, 1, 25, 1, 10, 24, 7, 1, 27, 1, 1, 29, 15, 1, 34, 1, 1, 28, 1, 8, 42, 1, 4, 30, 1, 1, 33, 1, 17, 32, 1, 1
OFFSET
1,4
FORMULA
a(n) = (1/5) * Sum_{d | 5*n-2, d==1 (mod 5)} (d+4).
G.f.: Sum_{k>0} x^k / (1 - x^(5*k-2))^2.
MATHEMATICA
a[n_] := DivisorSum[5*n - 2, # + 4 &, Mod[#, 5] == 1 &]/5; Array[a, 100] (* Amiram Eldar, Jul 12 2023 *)
PROG
(PARI) a(n) = sumdiv(5*n-2, d, (d%5==1)*(d+4))/5;
CROSSREFS
Sequence in context: A111956 A024564 A084795 * A030184 A284373 A104610
KEYWORD
nonn
AUTHOR
Seiichi Manyama, Jul 04 2023
STATUS
approved