OFFSET
0,3
FORMULA
MATHEMATICA
nmax = 35; CoefficientList[Series[x/Sum[x^k/(1 + x^k)^2, {k, 1, nmax + 1}], {x, 0, nmax}], x]
nmax = 35; CoefficientList[Series[1/D[Log[Sum[x^(k (k + 1)/2), {k, 0, nmax}]], x], {x, 0, nmax}], x]
a[0] = 1; a[n_] := a[n] = -Sum[DivisorSum[k + 1, (-1)^(# + 1) # &] a[n - k], {k, 1, n}]; Table[a[n], {n, 0, 35}]
CROSSREFS
KEYWORD
sign
AUTHOR
Ilya Gutkovskiy, May 27 2020
STATUS
approved