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A363887 Number of divisors of 7*n-5 of form 7*k+3. 1
0, 1, 0, 0, 2, 0, 0, 2, 0, 0, 2, 0, 0, 2, 1, 0, 2, 0, 0, 2, 0, 0, 2, 0, 2, 2, 0, 0, 2, 0, 0, 2, 0, 0, 4, 0, 0, 2, 0, 0, 2, 1, 0, 2, 2, 0, 2, 0, 0, 2, 0, 0, 2, 0, 2, 2, 0, 0, 4, 0, 0, 2, 0, 0, 4, 0, 0, 2, 0, 0, 2, 0, 0, 2, 2, 2, 2, 0, 0, 2, 0, 0, 3, 0, 2, 2, 0, 0, 2, 0, 0, 2, 2, 0, 4, 0, 0, 2, 0, 0 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,5
LINKS
FORMULA
a(n) = A363805(7*n-5).
G.f.: Sum_{k>0} x^(3*k-1)/(1 - x^(7*k-4)).
MATHEMATICA
a[n_] := DivisorSum[7*n - 5, 1 &, Mod[#, 7] == 3 &]; Array[a, 100] (* Amiram Eldar, Jun 26 2023 *)
PROG
(PARI) a(n) = sumdiv(7*n-5, d, d%7==3);
CROSSREFS
Cf. A363805.
Sequence in context: A095808 A281453 A079807 * A341776 A116373 A341777
KEYWORD
nonn
AUTHOR
Seiichi Manyama, Jun 26 2023
STATUS
approved

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Last modified February 21 13:52 EST 2024. Contains 370235 sequences. (Running on oeis4.)