A067324 Third column of triangle A067323.

2, 7, 23, 76, 255, 869, 3003, 10504, 37128, 132430, 476102, 1723528, 6277505, 22988385, 84592275, 312636240, 1159979700, 4319218530, 16134883410, 60452176200, 227110782990, 855361970034, 3228982640478

Offset: 0

Author

Wolfdieter Lang, Feb 05 2002

Keywords

• nonn
• easy

Comments

Also third diagonal of triangle A028364.

Crossrefs

Cf. A000245 (second column).

Formula

a(n)= A067323(n+2, 2)= C(n+3)-(C(n+2)+C(n+1)), C(n) := A000108(n) (Catalan).

G.f.: (c(x)^3)*(1+c(x)), with c(x) g.f. of A000108 (Catalan).