OFFSET
1,3
COMMENTS
Sum of divisors of n of the form 2^j - 1 for j >= 1.
FORMULA
MATHEMATICA
nmax = 85; CoefficientList[Series[Sum[(2^k - 1) x^(2^k - 1)/(1 - x^(2^k - 1)), {k, 1, Floor[Log[2, nmax]] + 1}], {x, 0, nmax}], x] // Rest
Table[Sum[Mod[CatalanNumber[d], 2] d, {d, Divisors[n]}], {n, 1, 85}]
CROSSREFS
KEYWORD
nonn
AUTHOR
Ilya Gutkovskiy, Oct 19 2019
STATUS
approved