A341918 Number of strong triangulations of a fixed hexagon with n interior nodes.

1, 15, 155, 1410, 12165, 102548, 856205, 7128420, 59386655, 495973610, 4156326090, 34965061950, 295326872685, 2504471904060, 21322339850120, 182220932483936, 1562911922345700, 13451387178653575, 116149864521206475, 1006036370555080950, 8739349976276626707, 76128234963921173340

Offset

1,2

Links

Andrew Howroyd, Table of n, a(n) for n = 1..500

Formula

a(n) = 120*(67*n^2 + 138*n + 68)*(4*n+7)!/((3*n+12)!*(n-1)!).

Prog

(PARI) a(n) = {120*(67*n^2 + 138*n + 68)*(4*n+7)!/((3*n+12)!*(n-1)!)}

Crossrefs

Column k=3 of A341856.

Sequence in context: A323971 A006096 A346843 * A099915 A110557 A016304

Adjacent sequences: A341915 A341916 A341917 * A341919 A341920 A341921

Keyword

nonn

Author

Andrew Howroyd, Feb 23 2021

Status

approved