A363885 Number of divisors of 7*n-3 of form 7*k+2.

1, 0, 2, 0, 2, 0, 2, 0, 2, 0, 2, 1, 2, 0, 2, 0, 2, 0, 2, 0, 4, 0, 2, 0, 2, 0, 2, 0, 2, 2, 2, 0, 2, 0, 2, 0, 3, 0, 4, 0, 2, 0, 2, 0, 2, 0, 2, 2, 2, 0, 2, 0, 4, 0, 2, 0, 4, 0, 2, 0, 2, 0, 2, 0, 2, 2, 2, 0, 4, 0, 2, 0, 2, 0, 4, 1, 2, 0, 2, 0, 2, 0, 2, 2, 4, 0, 2, 0, 2, 0, 2, 0, 4, 0, 2, 0, 2, 0, 4, 0

Offset

1,3

Links

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

Formula

a(n) = A363795(7*n-3).

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

Mathematica

a[n_] := DivisorSum[7*n - 3, 1 &, Mod[#, 7] == 2 &]; Array[a, 100] (* Amiram Eldar, Jun 26 2023 *)

Prog

(PARI) a(n) = sumdiv(7*n-3, d, d%7==2);

Crossrefs

Cf. A363850, A363855, A363886.

Cf. A363795.

Sequence in context: A053472 A036664 A045843 * A181587 A096158 A264782

Adjacent sequences: A363882 A363883 A363884 * A363886 A363887 A363888

Keyword

nonn

Author

Seiichi Manyama, Jun 26 2023

Status

approved