OFFSET
1,2
FORMULA
a(n) = A279061(7*n-6).
G.f.: Sum_{k>0} x^k/(1 - x^(7*k-6)).
MATHEMATICA
a[n_] := DivisorSum[7*n - 6, 1 &, Mod[#, 7] == 1 &]; Array[a, 100] (* Amiram Eldar, Jun 25 2023 *)
PROG
(PARI) a(n) = sumdiv(7*n-6, d, d%7==1);
CROSSREFS
KEYWORD
nonn
AUTHOR
Seiichi Manyama, Jun 24 2023
STATUS
approved