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
KEYWORD
sign
AUTHOR
Paul D. Hanna, May 13 2005
STATUS
approved