OFFSET
2,2
LINKS
Alois P. Heinz, Table of n, a(n) for n = 2..473
FORMULA
a(n) ~ c * d^n * n^(n + 3/2), where d = 0.26695170015188549567... and c = 1.1281954524592228... - Vaclav Kotesovec, Jul 01 2019
MAPLE
b:= proc(u, o, t) option remember; series(`if`(u+o=0, x^t,
add(b(u+j-1, o-j, irem(t+1, 2)), j=1..o)+
add(b(u-j, o+j-1, 0)*x^t, j=1..u)), x, 2)
end:
a:= n-> coeff(b(n, 0$2), x, 1):
seq(a(n), n=2..25);
CROSSREFS
KEYWORD
nonn
AUTHOR
Alois P. Heinz, Jul 25 2018
STATUS
approved