[seqfan] Re: Number of Trees

[Richard Mathar]

I've placed a bfile into http://www.strw.leidenuniv.nl/~mathar/progs/b000055.txt
The Maple program is:

# maple: create b-file b000055.txt
# Richard J. Mathar, 2009-03-06
A000081 := proc(n)
	option remember ;
	local d, j;
	if n<=1 then
		n
	else
		add ( add(d*procname(d),d=numtheory[divisors](j)) *procname(n-j), j=1..n-1)/ (n-1) ;
	fi ;
end:

  	

A000055 := proc(nmax)
	local a81,n,t,a,j ;
	a81 := [seq(A000081(i),i=0..nmax)] ;
	a := [] ;
	for n from 0 to nmax do
		if n = 0 then
			t := 1+op(n+1,a81) ;
		else
			t := op(n+1,a81) ;
		fi;
		if type(n,even) then
			t := t-op(1+n/2,a81)^2/2 ;
			t := t+op(1+n/2,a81)/2 ;
		fi;
		for j from 0 to (n-1)/2 do
			t := t-op(j+1,a81)*op(n-j+1,a81) ;
		od:
		a := [op(a),t] ;
	od:
	a ;
end:

# maximum b-file elements: 1000
L := A000055(1000) ;
read("transforms3") ;
LISTTOBFILE("b000055.txt",L,0) ;