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A364084
Expansion of Sum_{k>0} k * x^(3*k) / (1 - x^(4*k-1)).
2
0, 0, 1, 0, 0, 3, 0, 0, 4, 0, 0, 5, 2, 0, 6, 0, 0, 7, 0, 5, 8, 0, 0, 9, 0, 0, 16, 0, 0, 11, 3, 0, 12, 7, 0, 13, 0, 0, 14, 0, 8, 22, 0, 0, 16, 0, 0, 26, 0, 0, 18, 0, 8, 19, 10, 0, 24, 0, 0, 21, 0, 11, 22, 9, 0, 23, 0, 0, 36, 0, 0, 34, 0, 0, 36, 13, 0, 27, 0, 0, 28, 0, 14, 29, 0, 11, 40, 0, 0, 46, 5, 0, 32, 0, 0
OFFSET
1,6
FORMULA
a(n) = (1/4) * Sum_{d | 4*n-3, d==3 (mod 4)} (d+1).
G.f.: Sum_{k>0} x^(3*k) / (1 - x^(4*k-1))^2.
MATHEMATICA
a[n_] := DivisorSum[4*n - 3, # + 1 &, Mod[#, 4] == 3 &]/4; Array[a, 100] (* Amiram Eldar, Jul 05 2023 *)
PROG
(PARI) a(n) = sumdiv(4*n-3, d, (d%4==3)*(d+1))/4;
CROSSREFS
Cf. A359240.
Sequence in context: A133109 A130208 A363155 * A288654 A259191 A240455
KEYWORD
nonn
AUTHOR
Seiichi Manyama, Jul 04 2023
STATUS
approved