A362845 Number of divisors of 7*n-2 of form 7*k+1.

1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 2, 1, 1, 2, 1, 2, 1, 1, 1, 1, 2, 2, 1, 1, 1, 3, 1, 1, 1, 2, 2, 1, 1, 1, 1, 2, 1, 3, 1, 1, 3, 1, 1, 1, 1, 3, 1, 1, 1, 2, 2, 1, 1, 2, 1, 3, 1, 1, 1, 2, 2, 3, 1, 1, 1, 2, 1, 1, 1, 2, 3, 1, 1, 2, 1, 2, 1, 2, 2, 1, 2, 2, 1, 1, 1, 5, 1, 1, 1, 1, 2, 1, 1, 2, 1, 2, 1, 3, 1, 1

Offset

1,6

Comments

Also number of divisors of 7*n-2 of form 7*k+5.

Links

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

Formula

a(n) = A279061(7*n-2) = A363807(7*n-2).

G.f.: Sum_{k>0} x^(5*k-4)/(1 - x^(7*k-6)).

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

Mathematica

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

Prog

(PARI) a(n) = sumdiv(7*n-2, d, d%7==1);

Crossrefs

Cf. A279061, A363807.

Sequence in context: A093997 A157196 A300410 * A293451 A063014 A286361

Adjacent sequences: A362842 A362843 A362844 * A362846 A362847 A362848

Keyword

nonn

Author

Seiichi Manyama, Jun 24 2023

Status

approved