901620585domain: NAppears in sequencesa(n) = 3*binomial(2n-1,n).at n=15A003409Central elements of the (1,2)-Pascal triangle A029635.at n=16A029651a(0) = 1; for n > 0, a(n) = binomial(n, floor(n/2)) + binomial(n-1, floor(n/2)).at n=32A050168