138446domain: NAppears in sequencesa(n) is the number of Dyck paths of semilength n+6 having its first peak at height n+1.at n=21A005557Absolute row sums of triangle A102587, which is equal to the matrix inverse of triangle A094531 (the right-hand side of trinomial table A027907).at n=21A102588144n^2 + 2n.at n=30A158132