|
%I #6 Oct 06 2013 13:58:42
%S 1,1,2,4,10,25,67,180,495,1375,3871,10993,31493,90843,263686,769466,
%T 2256135,6643082,19634705,58232350,173242381,516860717,1546035258,
%U 4635543843,13929569399,41943013047,126532961332,382396277940
%N Number of 1-2-3-4-5 trees with n edges and with thinning limbs. A 1-2-3-4-5 tree is an ordered tree with vertices of outdegree at most 5. A rooted tree with thinning limbs is such that if a node has k children, all its children have at most k children.
%C The sequences corresponding to k=2 (A090344), k=3 (A124497), k=4 (A124499), k=5 (this A124500), etc. approach sequence A124344, corresponding to ordered trees with thinning limbs.
%F In general, if M[k](z) is the g.f. of the 1-2-...-k trees with thinning limbs and C[k](z)=1+z*{C[k](z)}^k is the g.f. of the k-ary trees, then M[k](z)=M[k-1](z)*C[k](M[k-1]^(k-1)*z^k), M[1](z)=1/(1-z).
%o (PARI) {a(n)=local(k=5,M=1+x*O(x^n)); for(i=1,k,M=M*sum(j=0,n,binomial(i*j,j)/((i-1)*j+1)*(x^i*M^(i-1))^j)); polcoeff(M,n)} \\ _Paul D. Hanna_
%Y Cf. A090344, A124497, A124499, A124501, A124344.
%K nonn
%O 0,3
%A _Emeric Deutsch_ and _Louis Shapiro_, Nov 06 2006
|
