A081293 a(n) = A000108(n) + A014137(n).

2, 3, 6, 14, 37, 107, 329, 1055, 3486, 11780, 40510, 141286, 498524, 1776312, 6382292, 23097542, 84118037, 308049947, 1133682557, 4190570237, 15551547887, 57919961507, 216418821767, 811055485427, 3047804166425, 11481792822005

Offset: 0

Author

Antti Karttunen, Mar 17 2003

Keywords

• nonn

Links

• Guo-Niu Han, Enumeration of Standard Puzzles, 2011. [Cached copy]
• Guo-Niu Han, Enumeration of Standard Puzzles, arXiv:2006.14070 [math.CO], 2020.

Crossrefs

Cf. A000108, A014137, A081289.

Programs

PARI

Cat(n) = binomial(2*n, n)/(n+1); \\ A000108
a(n) = Cat(n)+sum(k=0, n, Cat(k)); \\ Michel Marcus, Apr 28 2020

Formula

a(n) = 2*A000108(n) + A014137(n-1). - Michel Marcus, Apr 28 2020