A363879 Number of divisors of 7*n-6 of form 7*k+2.

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

Offset

1,6

Comments

Also number of divisors of 7*n-6 of form 7*k+4.

Links

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

Formula

a(n) = A363795(7*n-6) = A363806(7*n-6).

G.f.: Sum_{k>0} x^(4*k-2)/(1 - x^(7*k-5)).

G.f.: Sum_{k>0} x^(2*k)/(1 - x^(7*k-3)).

Mathematica

a[n_] := DivisorSum[7*n - 6, 1 &, Mod[#, 7] == 2 &]; Array[a, 100] (* Amiram Eldar, Jun 25 2023 *)

Prog

(PARI) a(n) = sumdiv(7*n-6, d, d%7==2);

Crossrefs

Cf. A363795, A363806.

Sequence in context: A131743 A357860 A147648 * A366767 A113686 A361414

Adjacent sequences: A363876 A363877 A363878 * A363880 A363881 A363882

Keyword

nonn

Author

Seiichi Manyama, Jun 25 2023

Status

approved