|
|
A346654
|
|
a(n) = Bell(2*n,n).
|
|
3
|
|
|
1, 2, 94, 12351, 3188340, 1362057155, 869725707522, 775929767223352, 921839901090823112, 1406921223577401454239, 2682502220690005671884710, 6248503930824315386034050253, 17460431497766377837983159782652, 57647207262184459310081410522242310, 222006095854149044448961838142906736554
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
0,2
|
|
LINKS
|
|
|
FORMULA
|
a(n) ~ 4^n * exp((2/LambertW(2) - 3)*n) * n^(2*n) / (sqrt(1 + LambertW(2)) * LambertW(2)^(2*n)).
|
|
MAPLE
|
b:= proc(n, k) option remember; `if`(n=0, 1,
(1+add(binomial(n-1, j-1)*b(n-j, k), j=1..n-1))*k)
end:
a:= n-> b(2*n, n):
|
|
MATHEMATICA
|
Table[BellB[2*n, n], {n, 0, 20}]
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
|
|
STATUS
|
approved
|
|
|
|