OFFSET
1,6
LINKS
Antti Karttunen, Table of n, a(n) for n = 1..16384
FORMULA
Numerators of coefficients in expansion of Sum_{k>=2} x^(2*k) / (k * (1 - x^k)).
EXAMPLE
0, 0, 0, 1/2, 0, 5/6, 0, 3/4, 1/3, 7/10, 0, 5/4, 0, 9/14, 8/15, 7/8, 0, 10/9, ...
MATHEMATICA
nmax = 80; CoefficientList[Series[Sum[x^(2 k)/(k (1 - x^k)), {k, 2, nmax}], {x, 0, nmax}], x] // Numerator // Rest
PROG
(PARI) a(n) = numerator(sumdiv(n, d, if ((d>1) && (d<n), 1/d))); \\ Michel Marcus, May 14 2024
CROSSREFS
KEYWORD
nonn,frac
AUTHOR
Ilya Gutkovskiy, May 14 2024
STATUS
approved