

A283049


Numbers of configurations of A'Campo forests with codimension 1 and degree n>0.


4



0, 4, 48, 480, 4560, 42504, 393120, 3624768, 33390720, 307618740, 2835722032, 26162863584, 241614915360, 2233533229200, 20667453710400, 191422799835264, 1774573628661504, 16465220088660432, 152894968403313600, 1420856831349155200, 13213537097286612240
(list;
graph;
refs;
listen;
history;
text;
internal format)



OFFSET

0,2


COMMENTS

We can prove this using generating functions. a(n) is given also by 4*binomial(4n,n2), for n>1.


LINKS

Indranil Ghosh, Table of n, a(n) for n = 0..500
N. Combe, V. Jugé, Counting bicolored A'Campo forests, arXiv:1702.07672 [math.AG], 2017.


FORMULA

a(n) = 4*binomial(4n,n2), for n>1.


EXAMPLE

For n=2 the a(2)=4 solutions are the number of A'Campo forests with codimension 1 and degree 2.


MATHEMATICA

Table[4*Binomial[4n, n2], {n, 1, 23}] (* Indranil Ghosh, Feb 28 2017 *)


PROG

(PARI) a(n) = 4*binomial(4*n, n2) \\ Indranil Ghosh, Feb 28 2017


CROSSREFS

Sequence in context: A299603 A026942 A264727 * A159903 A099671 A196963
Adjacent sequences: A283046 A283047 A283048 * A283050 A283051 A283052


KEYWORD

nonn


AUTHOR

Noemie Combe, Feb 27 2017


STATUS

approved



