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A195154 G.f. A(x) satisfies: A(A(x)) = (1+x-x^2)*A(x). 0
1, 1, -2, 6, -30, 184, -1294, 10034, -83908, 746006, -6983600, 68360302, -696122684, 7345561204, -80074813040, 899590031932, -10394864935860, 123344285904634, -1500938535372826, 18709376854618500, -238664936823622052, 3113060999816038350 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

LINKS

Table of n, a(n) for n=1..22.

FORMULA

The series reversion of A(x) is -G(-x) where G(x) is the g.f. of A195440, which satisfies: G(x - x*G(x) - x*G(x)^2) = x.

EXAMPLE

G.f.: A(x) = x + x^2 - 2*x^3 + 6*x^4 - 30*x^5 + 184*x^6 - 1294*x^7 +...

where A(A(x)) = (1+x-x^2)*A(x) begins:

A(A(x)) = x + 2*x^2 - 2*x^3 + 3*x^4 - 22*x^5 + 148*x^6 - 1080*x^7 +...

The series reversion of A(x) begins:

-G(-x) = x - x^2 + 4*x^3 - 21*x^4 + 134*x^5 - 968*x^6 + 7662*x^7 +...

where G(x) is the g.f. of A195440.

PROG

(PARI) {a(n)=local(A, B, F); if(n<1, 0, F=x+x^2+x*O(x^n); A=F;

for(j=0, n, for(i=0, j, B=serreverse(A); A=(A+subst(B, x, A*(1+x-x^2) ))/2); A=round(A)); polcoeff(A, n, x))}

CROSSREFS

Cf. A195440, A107095.

Sequence in context: A293653 A246541 A112385 * A078700 A176719 A203000

Adjacent sequences:  A195151 A195152 A195153 * A195155 A195156 A195157

KEYWORD

sign

AUTHOR

Paul D. Hanna, Sep 23 2011

STATUS

approved

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Last modified December 6 14:15 EST 2019. Contains 329806 sequences. (Running on oeis4.)