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A006409 Number of rooted nonseparable maps with n + 4 edges and n + 1 vertices on the torus.
(Formerly M4742)
0
10, 190, 1568, 8344, 33580, 111100, 317680, 811096 (list; graph; refs; listen; history; text; internal format)
OFFSET

2,1

REFERENCES

N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

LINKS

Table of n, a(n) for n=2..9.

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

FORMULA

Conjecture: a(n) = 10 * binomial(n + 6, n) + 120 * binomial(n + 6, n - 1) + 328 * binomial(n + 6, n - 2) + 232 * binomial(n + 6, n - 3) [From Walsh]. - Sean A. Irvine, Apr 03 2017

CROSSREFS

Sequence in context: A121973 A223146 A239765 * A173813 A249643 A056174

Adjacent sequences:  A006406 A006407 A006408 * A006410 A006411 A006412

KEYWORD

nonn

AUTHOR

N. J. A. Sloane

STATUS

approved

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Last modified December 5 17:42 EST 2019. Contains 329768 sequences. (Running on oeis4.)