OFFSET
0,10
LINKS
Alois P. Heinz, Table of n, a(n) for n = 0..700
FORMULA
E.g.f.: Product_{k>=4} (1 + x^k/k!).
MAPLE
b:= proc(n, i) option remember; `if`(n=0, 1,
`if`(i>n, 0, b(n, i+1)+b(n-i, i+1)*binomial(n, i)))
end:
a:= n-> b(n, 4):
seq(a(n), n=0..30); # Alois P. Heinz, Apr 28 2021
MATHEMATICA
nmax = 30; CoefficientList[Series[Product[(1 + x^k/k!), {k, 4, nmax}], {x, 0, nmax}], x] Range[0, nmax]!
a[0] = 1; a[n_] := a[n] = -(n - 1)! Sum[DivisorSum[k, # (-#!)^(-k/#) &, # > 3 &] a[n - k]/(n - k)!, {k, 1, n}]; Table[a[n], {n, 0, 30}]
CROSSREFS
KEYWORD
nonn
AUTHOR
Ilya Gutkovskiy, Apr 28 2021
STATUS
approved