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A364092
Sum of divisors of 5*n-1 of form 5*k+1.
4
1, 1, 1, 1, 7, 1, 1, 1, 12, 1, 7, 1, 17, 1, 1, 1, 28, 1, 1, 12, 27, 1, 7, 1, 32, 1, 1, 1, 59, 1, 12, 1, 42, 1, 7, 1, 47, 22, 1, 1, 58, 12, 1, 1, 73, 1, 33, 1, 62, 1, 1, 1, 84, 1, 1, 32, 72, 1, 28, 1, 93, 1, 1, 12, 124, 1, 1, 1, 87, 1, 7, 1, 118, 42, 12, 1, 119, 1, 1, 22, 102, 1, 53, 1, 107, 12, 32, 1
OFFSET
1,5
FORMULA
a(n) = A284097(5*n-1).
G.f.: Sum_{k>0} (5*k-4) * x^(4*k-3) / (1 - x^(5*k-4)).
MATHEMATICA
a[n_] := DivisorSum[5*n - 1, # &, Mod[#, 5] == 1 &]; Array[a, 100] (* Amiram Eldar, Jul 17 2023 *)
PROG
(PARI) a(n) = sumdiv(5*n-1, d, (d%5==1)*d);
CROSSREFS
KEYWORD
nonn
AUTHOR
Seiichi Manyama, Jul 04 2023
STATUS
approved