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 A094026 #16 Jul 07 2024 19:13:27
%S A094026 0,1,10,11,110,111,1110,1111,11110,11111,111110,111111,1111110,
%T A094026 1111111,11111110,11111111,111111110,111111111,1111111110,1111111111,
%U A094026 11111111110,11111111111,111111111110,111111111111,1111111111110
%N A094026 Expansion of x(1+10x)/((1-x^2)(1-10x^2)).
%C A094026 The expansion of x(1+kx)/((1-x^2)(1-kx^2)) has a(n)=k^((n+1)/2)/(2(sqrt(k)-1))-(-sqrt(k))^(n+1)/(2(sqrt(k)+1))-(-1)^n/2-(k+1)/(2(k-1)).
%C A094026 First 4 positive members are the divisors of 6 (the first perfect number), written in base 2 (see A135652, A135653, A135654, A135655). - _Omar E. Pol_, May 04 2008
%H A094026 Vincenzo Librandi, <a href="/A094026/b094026.txt">Table of n, a(n) for n = 0..300</a>
%H A094026 <a href="/index/Rec#order_04">Index entries for linear recurrences with constant coefficients</a>, signature (0,11,0,-10).
%F A094026 a(n) = 10^(n/2)(5/9+sqrt(10)/18+(5/9-sqrt(10)/18)(-1)^n)-(-1)^n/2-11/18.
%t A094026 LinearRecurrence[{0, 11, 0, -10}, {0, 1, 10, 11}, 30] (* _Vincenzo Librandi_, Apr 25 2019 *)
%t A094026 CoefficientList[Series[x (1+10x)/((1-x^2)(1-10x^2)),{x,0,30}],x] (* _Harvey P. Dale_, Jul 07 2024 *)
%o A094026 (Magma) I:=[0,1,10,11]; [n le 4 select I[n] else 11*Self(n-2)-10*Self(n-4): n in [1..30]]; // _Vincenzo Librandi_, Apr 25 2019
%Y A094026 Cf. A075427, A094025, A080610.
%K A094026 easy,nonn
%O A094026 0,3
%A A094026 _Paul Barry_, Apr 22 2004