OFFSET
0,2
COMMENTS
Equals the self-convolution 7th power of A106227. What is the frequency of occurrence of the nonzero digits?
EXAMPLE
A(x) = 1 + 7*x + x^7 + 4*x^14 + 6*x^21 + 5*x^28 + x^35 + 6*x^42 +...
A(x)^(1/7) = 1 + x - 3*x^2 + 13*x^3 - 65*x^4 + 351*x^5 - 1989*x^6 +-...
A106227 = {1,1,-3,13,-65,351,-1989,11650,-69900,427167,...}.
PROG
(PARI) {a(n)=local(A=1+7*x); if(n==0, 1, for(j=1, n, for(k=0, 6, t=polcoeff((A+k*x^j+x*O(x^j))^(1/7), j); if(denominator(t)==1, A=A+k*x^j; break))); return(polcoeff(A+x*O(x^n), n)))}
CROSSREFS
KEYWORD
nonn
AUTHOR
Paul D. Hanna, May 01 2005
STATUS
approved