[seqfan] Inversion Formula for Peculiar G.F. - Help

Ralf Stephan ralf at ark.in-berlin.de
Sat Jan 15 12:37:37 CET 2005


> What is the non-recursive inversion of the equation:
>  
> F(x) = (1-x) + a(1)*x*(1-x)(1-2x) + a(2)*x^2*(1-x)(1-2x)(1-3x) + ...
>              + a(n)*x^n*(1-x)(1-2x)(1-3x)*..*(1-(n+1)x) + ...
>  
> Knowing F(x), can one determine a(n) without recursion?

If so, this may not be too important. G.f.s of bifurcative ('divide-and-
conquer') sequences are resulting from Mahler-type functional equations,
and resolving the recursion iteratively gets you g.f.s with infinite sums. 
That does not help with asymptotics which, as Valery Liskovets remarked,
is what the folks out there need.


ralf






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