946844533674domain: NAppears in sequencesa(n) = 3*(2*n)!/((n+2)!*(n-1)!).at n=23A000245a(n) = 3*binomial(2n, n-1)/(n+2), n > 0, with a(0)=1.at n=23A071724Row sums of the inverse of number triangle A(n,k) = 1/C(n) if k <= n <= 2k, 0 otherwise, where C(n) = A000108(n).at n=24A127768a(n) = 3*C(4*n-2,2*n)/(2*n+1) - 2*0^n.at n=12A127769