OFFSET
0,2
EXAMPLE
A(x) = 1 + 3*x + 3*x^2 + 6*x^3 + 3*x^4 + 6*x^5 + 6*x^6 +...
A(x)^2 = 1 + 6*x + 15*x^2 + 30*x^3 + 51*x^4 + 66*x^5 +...
A(x)^2 (mod 4) = 1 + 2*x + 3*x^2 + 2*x^3 + 3*x^4 + 2*x^5 +...
G(x) = 1 + 6*x + 3*x^2 + 2*x^3 + 3*x^4 + 6*x^5 +...
where G(x) is the g.f. of A083946.
PROG
(PARI) {a(n)=local(d=2, m=6, A=1+m*x); for(j=2, d*n, for(k=1, m, t=polcoeff((A+k*x^j+x*O(x^j))^(1/m), j); if(denominator(t)==1, A=A+k*x^j; break))); polcoeff(A, d*n)}
CROSSREFS
KEYWORD
nonn
AUTHOR
Robert G. Wilson v and Paul D. Hanna, Aug 30 2005
STATUS
approved