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 A010680 #46 Feb 06 2024 11:58:51 %S A010680 0,9,0,9,0,9,0,9,0,9,0,9,0,9,0,9,0,9,0,9,0,9,0,9,0,9,0,9,0,9,0,9,0,9, %T A010680 0,9,0,9,0,9,0,9,0,9,0,9,0,9,0,9,0,9,0,9,0,9,0,9,0,9,0,9,0,9,0,9,0,9, %U A010680 0,9,0,9,0,9,0,9,0,9,0,9,0,9,0,9,0,9,0,9,0,9,0,9,0,9,0,9,0,9,0,9,0,9,0,9 %N A010680 Decimal expansion of 1/11. %C A010680 Period 2: repeat [0,9]. %H A010680 <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (0,1). %F A010680 a(n) = (9/2)*(1 - (-1)^n) = 9*(n mod 2). - _Paolo P. Lava_, Oct 31 2006 %F A010680 From _Elmo R. Oliveira_, Jan 15 2024: (Start) %F A010680 a(n) = a(n-2) for n >= 2. %F A010680 a(n) = 3 * A010674(n). %F A010680 G.f.: 9*x/(1-x^2). %F A010680 E.g.f.: 9*sinh(x). (End) %F A010680 a(n) = 9 * A000035(n). - _Alois P. Heinz_, Jan 16 2024 %e A010680 1/11 = 0.0909090909090909090909090909090909090909090909090909090909... %t A010680 RealDigits[1/11, 10, 100][[1]] (* _Alonso del Arte_, Mar 11 2018 *) %o A010680 (PARI) a(n) = 9*(n%2); \\ _Altug Alkan_, Mar 25 2018 %Y A010680 Cf. A000035, A010674. %Y A010680 Bisections give: A000004, A010734. %K A010680 nonn,easy,cons %O A010680 0,2 %A A010680 _N. J. A. Sloane_