A004305 - OEIS

A004305

Simple triangulations of a disk: column 4 of square array in A210664.
(Formerly M3091)

3, 22, 85, 254, 644, 1448, 2967, 5645, 10109, 17214, 28093, 44212, 67430, 100064, 144959, 205563, 286007, 391190, 526869, 699754, 917608, 1189352, 1525175, 1936649, 2436849, 3040478, 3763997, 4625760, 5646154, 6847744, 8255423, 9896567, 11801195, 14002134, 16535189, 19439318, 22756812, 26533480, 30818839

(list; graph; refs; listen; history; text; internal format)

OFFSET

0,1

REFERENCES

N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

LINKS

Andrew Howroyd, Table of n, a(n) for n = 0..1000

P. N. Rathie, A census of simple planar triangulations, J. Combin. Theory, B 16 (1974), 134-138.

FORMULA

a(n) = (n^6 + 15*n^5 + 103*n^4 + 405*n^3 + 976*n^2 + 1236*n + 432)/144.

CROSSREFS

Cf. A210664.