422030545335
domain: N
Appears in sequences
- a(n) = binomial(3*n,n)/(2*n+1) (enumerates ternary trees and also noncrossing trees).at n=17A001764
- If n = 2*m then a(n) = binomial(3*m, m)/(2*m+1), if n=2*m+1 then a(n) = binomial(3*m+1, m+1)/(2*m+1).at n=34A047749
- Expansion of series reversion of generating function for triangular numbers.at n=17A179848