OFFSET
0,2
FORMULA
a(n) = Sum_{k=0..n} (n - k)! * Sum_{j=0..n-k} binomial(n - k, j) * k^j / j!.
MAPLE
A343848List := proc(n) local T; T := proc(n, k) option remember;
if n = k then return 1 elif n = k+1 then return k+1 fi;
(2*n-k-1)*T(n-1, k) - (n-k-1)^2*T(n-2, k) end:
seq(add(T(k, j), j = 0..k), k = 0..n) end: A343848List(21);
MATHEMATICA
a[n_] := Sum[(n - k)! LaguerreL[n - k, -k], {k, 0, n}];
Table[a[n], {n, 0, 21}]
PROG
(PARI)
a(n) = sum(k=0, n, (n - k)!*sum(j=0, n - k, binomial(n - k, j) * k^j / j!))
for(n=0, 21, print(a(n)))
CROSSREFS
KEYWORD
nonn
AUTHOR
Peter Luschny, May 08 2021
STATUS
approved