1032004domain: NAppears in sequencesGeneralized Catalan numbers: a(n+1) = a(n) + Sum_{k=1..n-1} a(k)*a(n-1-k).at n=19A004148Number of elevated peakless Motzkin paths.at n=21A203019Expansion of (1 - x - x^2 - sqrt((1 - x - x^2)^2 - 4*x^3))/(2*x^3) in powers of x.at n=18A292460