A006432 Number of tree-rooted planar maps with 3 vertices and n faces and no isthmuses. (Formerly M3166)

0, 3, 60, 650, 5352, 37681, 239752, 1421226, 7996160, 43219990, 226309800, 1154900708, 5769562736, 28312118565, 136830224464, 652656300122, 3077631550512, 14367512295274, 66478236840680, 305161336656876, 1390869368495728, 6298727501142218, 28358908010334960

Offset

1,2

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..100

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) seems to be divisible by n+1. - Ralf Stephan, Sep 01 2003

Crossrefs

A diagonal of A342987.

Sequence in context: A229749 A283381 A002738 * A360577 A195550 A377677

Adjacent sequences: A006429 A006430 A006431 * A006433 A006434 A006435

Keyword

nonn

Author

N. J. A. Sloane

Extensions

Name clarified and terms a(13) and beyond from Andrew Howroyd, Apr 06 2021

Status

approved