OFFSET
0,2
FORMULA
a(n) = (exp(1) * Gamma(n + 1, 1) * Gamma(2*n + 1)) / Gamma(n + 1)^2.
a(n) * n! = A367962(2*n, n).
MAPLE
a := n -> add((2*n)!/(n!*(n-j)!), j = 0..n):
seq(a(n), n = 0..18);
MATHEMATICA
Table[Sum[(2n)!/(n!(n-j)!), {j, 0, n}], {n, 0, 20}] (* Harvey P. Dale, Feb 10 2024 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Peter Luschny, Dec 06 2023
STATUS
approved