A005027 - OEIS

A005027

Number of trivalent maps with n nodes.
(Formerly M1294)

1, 2, 4, 16, 63, 328, 1933, 12633, 87466, 633015, 4717745, 35980100, 279418926, 2202903618, 17590599410, 142025760202, 1157868883224, 9520828261067, 78888071847324, 658158709983945, 5525145717439001, 46644670326913204, 395812792437224022, 3374572617006946447

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

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)

FORMULA

a(n) = (A005028(n) + A341855(n))/2. - Andrew Howroyd, Feb 22 2021

PROG

(PARI) \\ See link in A169808 for script.

A169808AntidiagonalSums(25) \\ Andrew Howroyd, Feb 22 2021

CROSSREFS

Antidiagonal sums of array in A169808.

Sequence in context: A153963 A153960 A339648 * A153969 A153966 A138867

Adjacent sequences: A005024 A005025 A005026 * A005028 A005029 A005030

KEYWORD

nonn

AUTHOR

N. J. A. Sloane

EXTENSIONS

a(10) corrected and terms a(11) and beyond from Andrew Howroyd, Feb 22 2021

STATUS

approved