A004305 Simple triangulations of a disk: column 4 of square array in A210664.

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

Offset: 0

Author

N. J. A. Sloane

Keywords

• nonn

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.

Crossrefs

Cf. A210664.

Formula

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

Extensions

Entry revised by N. J. A. Sloane, Mar 27 2012