OFFSET
0,2
FORMULA
Limit_{n->infinity} a(n)^(1/n^2) = r^(r^2/(1-2*r)) = 1.533628065110458582..., where r = A220359 = 0.70350607643066243096929661621777... is the real root of the equation (1-r)^(2*r-1) = r^(2*r).
MATHEMATICA
Table[Sum[Binomial[Binomial[n, k], k], {k, 0, n}], {n, 0, 20}]
PROG
(PARI) a(n) = sum(k=0, n, binomial(binomial(n, k), k)); \\ Michel Marcus, Nov 19 2022
CROSSREFS
KEYWORD
nonn
AUTHOR
Vaclav Kotesovec, Nov 19 2022
STATUS
approved