OFFSET
1,3
FORMULA
G.f.: 1 - 1 / (1 + Sum_{k>=1} k^(k-2) * x^k).
MATHEMATICA
a[n_] := a[n] = n^(n - 2) - Sum[k^(k - 2) a[n - k], {k, 1, n - 1}]; Table[a[n], {n, 1, 20}]
nmax = 20; CoefficientList[Series[1 - 1/(1 + Sum[k^(k - 2) x^k, {k, 1, nmax}]), {x, 0, nmax}], x] // Rest
CROSSREFS
KEYWORD
nonn
AUTHOR
Ilya Gutkovskiy, Feb 07 2020
STATUS
approved