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A363879
Number of divisors of 7*n-6 of form 7*k+2.
0
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.
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
Sequence in context: A131743 A357860 A147648 * A366767 A113686 A361414
KEYWORD
nonn
AUTHOR
Seiichi Manyama, Jun 25 2023
STATUS
approved