OFFSET
3,2
COMMENTS
a(n) is the number of ways to place n indistinguishable balls into n distinguishable boxes with at least 2 boxes remaining empty and not all balls placed in one box.
MATHEMATICA
Table[Binomial[2*n - 1, n] - n^2 - 1, {n, 3, 30}] (* Wesley Ivan Hurt, Jan 20 2024 *)
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Enrique Navarrete, Dec 31 2022
STATUS
approved