%I #15 Dec 12 2023 08:05:28
%S 0,6,0,6,0,0,3,3,0,0,6,0,6,0,0,3,3,0,0,6,0,6,0,0,3,3,0,0,6,0,6,0,0,3,
%T 3,0,0,6,0,6,0,0,3,3,0,0,6,0,6,0,0,3,3,0,0,6,0,6,0,0,3,3,0,0,6,0,6,0,
%U 0,3,3,0,0,6,0,6,0,0,3,3,0,0,6,0,6,0,0,3,3,0,0,6,0,6,0,0,3,3,0,0,6,0,6,0,0
%N Period 9: repeat [0, 6, 0, 6, 0, 0, 3, 3, 0].
%C Also the continued fraction expansion of 6+sqrt(3970)/10 (dropping a(0)).
%C Also the decimal expansion of 6733370/111111111.
%H <a href="/index/Rec">Index entries for linear recurrences with constant coefficients</a>, signature (0,0,0,0,0,0,0,0,1).
%F a(n) = ( A061037(n)*A061037(n+1) ) mod 9.
%F a(n) = a(n-9). G.f.: -3*x*(2+2*x^2+x^5+x^6)/((x-1)*(1+x+x^2)*(x^6+x^3+1)).
%Y Cf. A157742, A158012, A158068.
%K nonn,easy,less
%O 0,2
%A _Paul Curtz_, Mar 12 2009
%E A-number in the formula corrected by _R. J. Mathar_, Sep 11 2009