OFFSET
0,4
LINKS
Alois P. Heinz, Table of n, a(n) for n = 0..480
FORMULA
MAPLE
g:= proc(n) option remember; `if`(n=0, 1,
add(g(n-j)*binomial(n-1, j-1), j=2..n))
end:
b:= proc(n, m) option remember; `if`(n=0,
g(m), m*b(n-1, m)+b(n-1, m+1))
end:
a:= n-> b(n, 0):
seq(a(n), n=0..23); # Alois P. Heinz, Aug 27 2021
# second Maple program:
b:= proc(n, t) option remember; `if`(n=0, 1, add(b(n-j, t)*
`if`(t=0, 1, b(j, 0)-1)*binomial(n-1, j-1), j=1..n))
end:
a:= n-> b(n, 1):
seq(a(n), n=0..23); # Alois P. Heinz, Sep 02 2021
MATHEMATICA
nmax = 23; CoefficientList[Series[Exp[Exp[Exp[x] - 1] - Exp[x]], {x, 0, nmax}], x] Range[0, nmax]!
a[0] = 1; a[n_] := a[n] = Sum[Binomial[n - 1, k - 1] (BellB[k] - 1) a[n - k], {k, 1, n}]; Table[a[n], {n, 0, 23}]
PROG
(PARI) my(x='x+O('x^25)); Vec(serlaplace(exp(exp(exp(x)-1)-exp(x)))) \\ Michel Marcus, Aug 27 2021
CROSSREFS
KEYWORD
nonn
AUTHOR
Ilya Gutkovskiy, Aug 27 2021
STATUS
approved