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A359326
Number of divisors of 6*n-4 of form 6*k+5.
5
0, 0, 0, 1, 0, 0, 0, 1, 1, 0, 0, 1, 0, 1, 0, 1, 0, 0, 2, 1, 0, 0, 0, 2, 0, 0, 0, 1, 2, 1, 0, 1, 0, 1, 0, 1, 0, 0, 2, 1, 1, 0, 0, 2, 0, 1, 0, 1, 2, 0, 0, 2, 0, 1, 0, 1, 0, 0, 2, 1, 0, 1, 2, 2, 0, 0, 0, 1, 2, 0, 0, 1, 0, 2, 0, 1, 0, 1, 2, 2, 0, 0, 0, 2, 2, 0, 0, 1, 2, 0
OFFSET
1,19
LINKS
FORMULA
a(n) = A319995(6*n-4).
G.f.: Sum_{k>0} x^(4*k)/(1 - x^(6*k-1)).
G.f.: Sum_{k>0} x^(5*k-1)/(1 - x^(6*k-2)).
MATHEMATICA
a[n_] := DivisorSum[6*n-4, 1 &, Mod[#, 6] == 5 &]; Array[a, 100] (* Amiram Eldar, Aug 14 2023 *)
PROG
(PARI) a(n) = sumdiv(6*n-4, d, d%6==5);
(PARI) my(N=100, x='x+O('x^N)); concat([0, 0, 0], Vec(sum(k=1, N, x^(4*k)/(1-x^(6*k-1)))))
(PARI) my(N=100, x='x+O('x^N)); concat([0, 0, 0], Vec(sum(k=1, N, x^(5*k-1)/(1-x^(6*k-2)))))
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Seiichi Manyama, Dec 25 2022
STATUS
approved