OFFSET
1,2
LINKS
Seiichi Manyama, Table of n, a(n) for n = 1..10000
MATHEMATICA
a[n_] := DivisorSum[n, #^2 &, Mod[#, 3] == 2 &]; Array[a, 100] (* Amiram Eldar, Jun 30 2023 *)
PROG
(PARI) a(n) = sumdiv(n, d, (d%3==2)*d^2); \\ Seiichi Manyama, Jun 30 2023
CROSSREFS
KEYWORD
nonn
AUTHOR
Ralf Stephan, Feb 11 2005
STATUS
approved