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A363850
Number of divisors of 7*n-3 of form 7*k+1.
2
1, 1, 1, 1, 2, 1, 1, 1, 2, 1, 1, 1, 3, 1, 1, 1, 2, 1, 1, 1, 3, 1, 1, 2, 2, 1, 1, 1, 3, 1, 1, 1, 2, 1, 2, 1, 3, 1, 2, 1, 2, 1, 1, 1, 3, 2, 1, 1, 2, 1, 1, 1, 3, 2, 1, 1, 4, 1, 1, 1, 3, 1, 1, 1, 2, 1, 1, 2, 4, 1, 1, 1, 2, 1, 2, 1, 3, 1, 3, 1, 2, 1, 1, 2, 3, 1, 1, 1, 2, 2, 1, 1, 4, 1, 1, 1, 2, 1, 2, 1
OFFSET
1,5
COMMENTS
Also number of divisors of 7*n-3 of form 7*k+4.
FORMULA
a(n) = A279061(7*n-3) = A363806(7*n-3).
G.f.: Sum_{k>0} x^(4*k-3)/(1 - x^(7*k-6)).
G.f.: Sum_{k>0} x^k/(1 - x^(7*k-3)).
MATHEMATICA
a[n_] := DivisorSum[7*n - 3, 1 &, Mod[#, 7] == 1 &]; Array[a, 100] (* Amiram Eldar, Jun 25 2023 *)
PROG
(PARI) a(n) = sumdiv(7*n-3, d, d%7==1);
CROSSREFS
Sequence in context: A327499 A353693 A327857 * A227481 A143654 A170981
KEYWORD
nonn
AUTHOR
Seiichi Manyama, Jun 24 2023
STATUS
approved