OFFSET
1,2
FORMULA
a(n) = A050452(4*n-2).
G.f.: Sum_{k>0} (4*k-1) * x^(2*k) / (1 - x^(4*k-1)).
MATHEMATICA
a[n_] := DivisorSum[4*n - 2, # &, Mod[#, 4] == 3 &]; Array[a, 100] (* _Amiram Eldar_, Jul 08 2023 *)
PROG
(PARI) a(n) = sumdiv(4*n-2, d, (d%4==3)*d);
CROSSREFS
KEYWORD
nonn
AUTHOR
_Seiichi Manyama_, Jul 08 2023
STATUS
approved