A005509 - OEIS

A005509

Number of unrooted triangulations with reflection symmetry of a disk with 2 internal nodes and n+3 nodes on the boundary.
(Formerly M3312)

1, 4, 7, 18, 26, 68, 91, 248, 318, 900, 1122, 3278, 4004, 12012, 14443, 44304, 52598, 164424, 193154, 613700, 714476, 2302344, 2659582, 8677072, 9954860, 32836180, 37442160, 124715430, 141430680, 475237500, 536257995, 1816267680, 2040199590, 6959878200

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

OFFSET

0,2

REFERENCES

C. F. Earl and L. J. March, Architectural applications of graph theory, pp. 327-355 of R. J. Wilson and L. W. Beineke, editors, Applications of Graph Theory. Academic Press, NY, 1979.

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..500

C. F. Earl and L. J. March, Architectural applications of graph theory, pp. 327-355 of R. J. Wilson and L. W. Beineke, editors, Applications of Graph Theory. Academic Press, NY, 1979. (Annotated scanned copy)

C. F. Earl & N. J. A. Sloane, Correspondence, 1980-1981

CROSSREFS

Row n=2 of the array in A169809.

Sequence in context: A276187 A357041 A318025 * A147366 A056318 A011948

Adjacent sequences: A005506 A005507 A005508 * A005510 A005511 A005512

KEYWORD

nonn

AUTHOR

N. J. A. Sloane

EXTENSIONS

Terms a(6) and beyond from Andrew Howroyd, Feb 22 2021

STATUS

approved