OFFSET
0,2
EXAMPLE
A(x) = 1 + 4*x + 2*x^2 - x^4 + 2*x^6 - 5*x^8 + 12*x^10 - 30*x^12 +...
A(x^2)^(1/2) = 1 + 2*x^2 - x^4 + 2*x^6 - 5*x^8 + 12*x^10 - 30*x^12 +...
PROG
(PARI) {a(n)=local(A=1+x); for(i=1, n, A=subst(A, x, x^2)^(1/2)+4*x+x*O(x^n)); polcoeff(A, n, x)}
CROSSREFS
KEYWORD
sign
AUTHOR
Paul D. Hanna, May 11 2005
STATUS
approved