A107099 G.f. satisfies A(A(x)) = x + 4*x^3, where A(x) = Sum_{n>=0} a(n)*x^(2*n+1).

1, 2, -6, 36, -266, 2028, -13596, 50088, 566694, -16598580, 232284876, -1912070088, 631155132, 239439857272, -2781218767224, -17362458802992, 795693633448710, -458070639409908, -335724554310292548, 4520379769156382616, 109439050270732883028, -3828757746830590219608

Offset: 0

Author

Paul D. Hanna, May 13 2005

Keywords

• sign

Comments

Coefficients [x^n] A(x) = 0 (mod 3) except at n = 3^k (conjecture).

Examples

			A(x) = 1*x + 2*x^3 - 6*x^5 + 36*x^7 - 266*x^9 + 2028*x^11 - 13596*x^13 +-...
		

Links

• Seiichi Manyama, Table of n, a(n) for n = 0..433

Crossrefs

Cf. A027436, A097090.

Programs

PARI

b(n) = local(A,B,F);F=x+4*x^3+x*O(x^n);A=F;if(n==0,0, for(i=0,n,B=serreverse(A);A=(A+subst(B,x,F))/2);polcoeff(A,n,x));
a(n) = b(2*n+1);