31030387440domain: NAppears in sequencesSum of adjacent Catalan numbers.at n=20A005807Expansion of (1+x^2*C)*C, where C = (1-(1-4*x)^(1/2))/(2*x) is g.f. for Catalan numbers, A000108.at n=21A071716The matrix-vector product A133080 * A000108.at n=21A133602Expansion of (1+x)*c(x), c(x) the g.f. of A000108.at n=21A167422