A363053 - OEIS

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A363053

Sum of divisors of 5*n-4 of form 5*k+3.

0, 3, 0, 8, 3, 13, 0, 21, 0, 23, 3, 36, 0, 36, 0, 38, 3, 43, 13, 59, 0, 53, 3, 58, 0, 84, 0, 76, 3, 73, 0, 94, 23, 83, 3, 96, 0, 96, 0, 126, 3, 103, 0, 137, 13, 113, 36, 118, 0, 126, 0, 136, 3, 171, 0, 164, 0, 156, 3, 156, 43, 174, 0, 158, 3, 163, 0, 255, 0, 173, 16, 178, 0, 186, 53, 196, 3, 193, 23, 252

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OFFSET

1,2

LINKS

Table of n, a(n) for n=1..80.

FORMULA

a(n) = A284281(5*n-4).

G.f.: Sum_{k>0} (5*k-2) * x^(2*k) / (1 - x^(5*k-2)).

MATHEMATICA

a[n_] := DivisorSum[5*n - 4, # &, Mod[#, 5] == 3 &]; Array[a, 100] (* Amiram Eldar, Jul 06 2023 *)

PROG

(PARI) a(n) = sumdiv(5*n-4, d, (d%5==3)*d);