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 A283049 Numbers of configurations of A'Campo forests with co-dimension 1 and degree n>0. 4

%I

%S 0,4,48,480,4560,42504,393120,3624768,33390720,307618740,2835722032,

%T 26162863584,241614915360,2233533229200,20667453710400,

%U 191422799835264,1774573628661504,16465220088660432,152894968403313600,1420856831349155200,13213537097286612240

%N Numbers of configurations of A'Campo forests with co-dimension 1 and degree n>0.

%C We can prove this using generating functions. a(n) is given also by 4*binomial(4n,n-2), for n>1.

%H Indranil Ghosh, <a href="/A283049/b283049.txt">Table of n, a(n) for n = 0..500</a>

%H N. Combe, V. JugĂ©, <a href="http://arxiv.org/abs/1702.07672">Counting bi-colored A'Campo forests</a>, arXiv:1702.07672 [math.AG], 2017.

%F a(n) = 4*binomial(4n,n-2), for n>1.

%e For n=2 the a(2)=4 solutions are the number of A'Campo forests with co-dimension 1 and degree 2.

%t Table[4*Binomial[4n,n-2],{n,1,23}] (* _Indranil Ghosh_, Feb 28 2017 *)

%o (PARI) a(n) = 4*binomial(4*n,n-2) \\ _Indranil Ghosh_, Feb 28 2017

%K nonn

%O 0,2

%A _Noemie Combe_, Feb 27 2017

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Last modified January 30 19:01 EST 2023. Contains 359947 sequences. (Running on oeis4.)