A141149 G.f. satisfies: A(x) = x*(1 + A(A(x)))/(1 - A(A(x))).

1, 2, 10, 74, 682, 7274, 86386, 1116338, 15464818, 227315378, 3519165370, 57067589306, 965272138714, 16974057490010, 309490272908386, 5838392491816418, 113747315349651298, 2285212240930687202

Offset

1,2

Links

Table of n, a(n) for n=1..18.

Formula

G.f. satisfies: A( x*(1 - A(x))/(1 + A(x)) ) = x.

Example

A(x) = x + 2*x^2 + 10*x^3 + 74*x^4 + 682*x^5 + 7274*x^6 + 86386*x^7 +...
A(A(x)) = x + 4*x^2 + 28*x^3 + 256*x^4 + 2752*x^5 + 33124*x^6 + 434524*x^7 +...
The series reversion of A(x) equals:
x*(1-A(x))/(1+A(x)) = x - 2*x^2 - 2*x^3 - 14*x^4 - 110*x^5 - 1058*x^6 -...

Prog

(PARI) {a(n)=local(A=x+x^2); if(n<1, 0, for(i=1, n, A=serreverse(x*((1-A)/(1+A+x*O(x^n))))); polcoeff(A, n))}

Crossrefs

Sequence in context: A192259 A245901 A352914 * A306045 A152408 A046863

Adjacent sequences: A141146 A141147 A141148 * A141150 A141151 A141152

Keyword

nonn

Author

Paul D. Hanna, Jun 11 2008

Status

approved