A005028 Number of symmetric trivalent maps with n nodes. (Formerly M1257)

1, 2, 4, 12, 33, 102, 312, 1010, 3256, 10836, 36094, 122544, 417150, 1437712, 4970904, 17333772, 60638124, 213435264, 753520804, 2672606464, 9505230397, 33928264990, 121400935184, 435660446342, 1566809204928, 5648450745204, 20402191885146, 73842311224632

Offset

3,2

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 = 3..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)

Crossrefs

Antidiagonal sums of the array in A169809.

Cf. A005027.

Sequence in context: A027695 A148195 A169807 * A231356 A148196 A148197

Adjacent sequences: A005025 A005026 A005027 * A005029 A005030 A005031

Keyword

nonn

Author

N. J. A. Sloane

Extensions

Terms a(11) and beyond from Andrew Howroyd, Feb 22 2021

Status

approved