OFFSET
0,3
EXAMPLE
1 + x + 2*x^2 + 4*x^3 + 9*x^4 + 20*x^5 + 45*x^6 + 101*x^7 + 228*x^8 + ...
MATHEMATICA
terms = 29; f[k_] := If[k >= 0, -x^a[k], 1]; F[m_] := ContinuedFractionK[ f[k], 1, {k, -1, m}]; s[0] = {a[0] -> 1}; eq[n_] := eq[n] = Normal[( F[n-1] /. s[n-1]) + O[x]^(n+1)] - Sum[a[k] x^k, {k, 0, n}] == 0 /. s[n-1]; s[n_] := s[n] = Join[s[n-1], SolveAlways[eq[n], x] [[1]]]; Reap[ Do[ Print["a(", n, ") = ", an = a[n] /. s[n]]; Sow[an], {n, 0, terms-1} ]][[2, 1]] (* Jean-François Alcover, Jul 16 2017 *)
CROSSREFS
KEYWORD
nonn,nice
AUTHOR
Michael Somos, Jun 10 2012
STATUS
approved