For the following test can be compared with the output of the following Mathematica commands.
rhxSolve[eqs_] :=
Module[{L, X, Sol, S, s, sc}, L = {0, 1, 2, 3, 4, 5, 6, 7, 8}; X = {x, 0, 8}; Sol = Solve[eqs, {A[x], B[x]}]; S[i_] := Sol[[1, i, 2]]; s[i_] := Series[S[i], X]; sc[i_, n_] := SeriesCoefficient[s[i], n]; ME[i_] := Map[#!*sc[i, #] &, L]; MO[i_] := Map[sc[i, #] &, L]; {SE1[ME[1]], SO1[MO[1]], SE2[ME[2]], SO2[MO[2]]} ] testRecursive2 = rhxSolve[{A[x] == 1 + x*B[x]^3, B[x] == 1 + x*A[x]^2}] testRecursive2b = rhxSolve[{A[x] == x + B[x]^3, B[x] == x + A[x]^2}] |
Look for fiWords on http://mupad-combinat.sourceforge.net/doc/en/index/guidedTour-predefinedCombinatorialClasses.html.
Solving the order equations for the generating series of the following system gives the orders (5,4,2) for (A,B,C).