[go: up one dir, main page]

login

Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).

E.g.f.: exp( exp(exp(x) - 1) - exp(x) ).
1

%I #12 Sep 03 2021 12:30:39

%S 1,0,1,4,17,91,587,4327,35604,323316,3210600,34574453,400893066,

%T 4975247460,65755573847,921535225267,13643496840808,212688569520955,

%U 3480978391442106,59657975022473437,1068151956803180295,19937983367649562025,387243759600707804811,7812456801157894913964

%N E.g.f.: exp( exp(exp(x) - 1) - exp(x) ).

%C Exponential transform of A058692.

%C Stirling transform of A000296.

%H Alois P. Heinz, <a href="/A347340/b347340.txt">Table of n, a(n) for n = 0..480</a>

%F a(0) = 1; a(n) = Sum_{k=1..n} binomial(n-1,k-1) * (Bell(k) - 1) * a(n-k).

%F a(n) = Sum_{k=0..n} Stirling2(n,k) * A000296(k).

%F a(n) = Sum_{k=0..n} binomial(n,k) * A000258(k) * A000587(n-k).

%p g:= proc(n) option remember; `if`(n=0, 1,

%p add(g(n-j)*binomial(n-1, j-1), j=2..n))

%p end:

%p b:= proc(n, m) option remember; `if`(n=0,

%p g(m), m*b(n-1, m)+b(n-1, m+1))

%p end:

%p a:= n-> b(n, 0):

%p seq(a(n), n=0..23); # _Alois P. Heinz_, Aug 27 2021

%p # second Maple program:

%p b:= proc(n, t) option remember; `if`(n=0, 1, add(b(n-j, t)*

%p `if`(t=0, 1, b(j, 0)-1)*binomial(n-1, j-1), j=1..n))

%p end:

%p a:= n-> b(n, 1):

%p seq(a(n), n=0..23); # _Alois P. Heinz_, Sep 02 2021

%t nmax = 23; CoefficientList[Series[Exp[Exp[Exp[x] - 1] - Exp[x]], {x, 0, nmax}], x] Range[0, nmax]!

%t 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}]

%o (PARI) my(x='x+O('x^25)); Vec(serlaplace(exp(exp(exp(x)-1)-exp(x)))) \\ _Michel Marcus_, Aug 27 2021

%Y Cf. A000110, A000166, A000258, A000296, A000587, A052852, A058692, A182386, A288268.

%K nonn

%O 0,4

%A _Ilya Gutkovskiy_, Aug 27 2021