This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A158090 #15 Dec 12 2023 08:05:28 %S A158090 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 A158090 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 A158090 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 A158090 Period 9: repeat [0, 6, 0, 6, 0, 0, 3, 3, 0]. %C A158090 Also the continued fraction expansion of 6+sqrt(3970)/10 (dropping a(0)). %C A158090 Also the decimal expansion of 6733370/111111111. %H A158090 <a href="/index/Rec">Index entries for linear recurrences with constant coefficients</a>, signature (0,0,0,0,0,0,0,0,1). %F A158090 a(n) = ( A061037(n)*A061037(n+1) ) mod 9. %F A158090 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 A158090 Cf. A157742, A158012, A158068. %K A158090 nonn,easy,less %O A158090 0,2 %A A158090 _Paul Curtz_, Mar 12 2009 %E A158090 A-number in the formula corrected by _R. J. Mathar_, Sep 11 2009