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%I #7 Mar 12 2015 22:29:03
%S 1,1,-3,13,-65,351,-1989,11650,-69900,427167,-2648438,16612947,
%T -105215448,671760933,-4318468133,27926126547,-181520036139,
%U 1185220461607,-7769787811032,51117085986564,-337373170566291,2233091754693676,-14819626688607761,98582852441111688
%N Self-convolution 7th power equals A106226, which consists entirely of digits {0,1,2,3,4,5,6} after the initial terms {1,7}.
%e A(x) = 1 + x - 3*x^2 + 13*x^3 - 65*x^4 + 351*x^5 - 1989*x^6 +-...
%e A(x)^7 = 1 + 7*x + x^7 + 4*x^14 + 6*x^21 + 5*x^28 + x^35 + 6*x^42 +...
%e A106226 = {1,7,0,0,0,0,0,1,0,0,0,0,0,0,4,0,0,0,0,0,0,6,...}.
%o (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))^(1/7),n)))}
%Y Cf. A106226, A106219, A106221, A106223, A106225.
%K sign,base
%O 0,3
%A _Paul D. Hanna_, May 01 2005
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