A006412 - OEIS

A006412

Number of nonseparable tree-rooted planar maps with n + 3 edges and 4 vertices.
(Formerly M3697)

4, 75, 604, 3150, 12480, 40788, 115500, 292578, 677820, 1459315, 2954952, 5679700, 10438272, 18449760, 31511880, 52213596, 84206100, 132543411, 204105220, 308116050, 456776320, 666022500, 956435220, 1354315950, 1892954700, 2614113099, 3569749200, 4824012424

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

OFFSET

1,1

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 = 1..1000

T. R. S. Walsh and A. B. Lehman, Counting rooted maps by genus. III: Nonseparable maps, J. Combinatorial Theory Ser. B 18 (1975), 222-259.

FORMULA

a(n) = 4 * binomial(n + 4, 5) + 51 * binomial(n + 4, 6) + 163 * binomial(n + 4, 7) + 194 * binomial(n + 4, 8) + 78 * binomial(n + 4, 9). - Sean A. Irvine, Apr 03 2017

a(n) = binomial(n+5,6)*(n + 3)*(13*n^2 + 57*n + 14)/84. - Andrew Howroyd, Apr 05 2021

PROG

(PARI) a(n) = {binomial(n+5, 6)*(n + 3)*(13*n^2 + 57*n + 14)/84} \\ Andrew Howroyd, Apr 05 2021

CROSSREFS

Column 4 of A342984.

Cf. A006411, A006413.

Sequence in context: A280889 A257367 A072373 * A206456 A137220 A006236

Adjacent sequences: A006409 A006410 A006411 * A006413 A006414 A006415

KEYWORD

nonn

AUTHOR

N. J. A. Sloane

EXTENSIONS

Terms a(11) and beyond from Andrew Howroyd, Apr 05 2021

STATUS

approved