login
A359307
Number of divisors of 6*n-3 of form 6*k+1.
5
1, 1, 1, 2, 1, 1, 2, 1, 1, 2, 2, 1, 2, 1, 1, 2, 1, 2, 2, 2, 1, 2, 1, 1, 3, 1, 1, 2, 2, 1, 2, 2, 2, 2, 1, 1, 2, 2, 2, 2, 1, 1, 2, 1, 1, 4, 2, 2, 2, 1, 1, 2, 2, 1, 2, 2, 1, 2, 2, 2, 2, 1, 2, 2, 2, 1, 4, 1, 1, 2, 1, 2, 2, 3, 1, 2, 1, 2, 2, 1, 2, 2, 2, 1, 3, 2, 1, 4, 1, 1
OFFSET
1,4
LINKS
FORMULA
a(n) = A279060(6*n-3).
G.f.: Sum_{k>0} x^k/(1 - x^(6*k-3)).
G.f.: Sum_{k>0} x^(3*k-2)/(1 - x^(6*k-5)).
MATHEMATICA
a[n_] := DivisorSum[6*n-3, 1 &, Mod[#, 6] == 1 &]; Array[a, 100] (* Amiram Eldar, Aug 16 2023 *)
PROG
(PARI) a(n) = sumdiv(6*n-3, d, d%6==1);
(PARI) my(N=100, x='x+O('x^N)); Vec(sum(k=1, N, x^k/(1-x^(6*k-3))))
(PARI) my(N=100, x='x+O('x^N)); Vec(sum(k=1, N, x^(3*k-2)/(1-x^(6*k-5))))
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Seiichi Manyama, Dec 25 2022
STATUS
approved