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

0,2

Comments

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

Links

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

Example

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

Prog

(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);

Crossrefs

Cf. A027436, A097090.

Sequence in context: A369091 A162697 A377533 * A143021 A007657 A234235

Adjacent sequences: A107096 A107097 A107098 * A107100 A107101 A107102

Keyword

sign

Author

Paul D. Hanna, May 13 2005

Status

approved