A363886 Number of divisors of 7*n-3 of form 7*k+5.

0, 0, 0, 1, 0, 0, 0, 0, 2, 0, 0, 0, 0, 2, 0, 0, 0, 0, 2, 0, 1, 0, 0, 2, 0, 0, 0, 0, 2, 0, 0, 0, 2, 2, 0, 0, 0, 0, 2, 0, 0, 0, 0, 2, 2, 0, 0, 0, 2, 0, 0, 1, 0, 2, 0, 0, 2, 0, 2, 0, 0, 0, 0, 2, 0, 0, 0, 0, 4, 0, 2, 0, 0, 2, 0, 0, 0, 0, 2, 0, 2, 0, 0, 2, 0, 0, 0, 0, 2, 2, 0, 0, 2, 2, 0, 0, 1, 0, 2, 0

Offset

1,9

Links

Table of n, a(n) for n=1..100.

Formula

a(n) = A363807(7*n-3).

G.f.: Sum_{k>0} x^(5*k-1)/(1 - x^(7*k-2)).

Mathematica

a[n_] := DivisorSum[7*n - 3, 1 &, Mod[#, 7] == 5 &]; Array[a, 100] (* Amiram Eldar, Jun 26 2023 *)

Prog

(PARI) a(n) = sumdiv(7*n-3, d, d%7==5);

Crossrefs

Cf. A363850, A363855, A363885.

Cf. A363807.

Sequence in context: A227186 A037134 A254612 * A227189 A359327 A234859

Adjacent sequences: A363883 A363884 A363885 * A363887 A363888 A363889

Keyword

nonn

Author

Seiichi Manyama, Jun 26 2023

Status

approved