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 A289122 #33 Aug 24 2017 15:51:50
%S A289122 0,0,0,1,0,1,1,1,2,1,2,2,2,2,3,2,3,3,3,4,3,4,4,4,4,5,4,5,5,5,6,5,6,6,
%T A289122 6,6,7,6,7,7,7,8,7,8,8,8,8,9,8,9,9,9,10,9,10,10,10,10,11,10,11,11,11,
%U A289122 12,11,12,12,12,12,13,12,13,13,13,14,13,14,14,14,14,15
%N A289122 a(n) is number of odd integers divisible by 11 in the interval ]2*(n-1)^2, 2*n^2[.
%C A289122 This sequence has the form (0+2k,0+2k,0+2k,1+2k,0+2k,1+2k,1+2k,1+2k,2+2k, 1+2k,2+2k) for k>=0.
%H A289122 <a href="/index/Rec#order_12">Index entries for linear recurrences with constant coefficients</a>, signature (1,0,0,0,0,0,0,0,0,0,1,-1).
%F A289122 a(n + 11*k) = a(n) + 2*k. - _David A. Corneth_, Jun 25 2017
%F A289122 G.f.: (x^10-x^9+x^8+x^5-x^4+x^3)/(x^12-x^11-x+1). - _Alois P. Heinz_, Jun 26 2017
%t A289122 Table[Count[Mod[Table[2((n-1)^2 +k) -1,{k,1,2n-1}],11],0],{n,0,50}]
%t A289122 LinearRecurrence[{1,0,0,0,0,0,0,0,0,0,1,-1},{0,0,0,1,0,1,1,1,2,1,2,2},90] (* _Harvey P. Dale_, Aug 24 2017 *)
%o A289122 (PARI) a(n) = sum(k=2*(n-1)^2, 2*n^2, ((k % 2) && ((k % 11) == 0))); \\ _Michel Marcus_, Jun 26 2017
%Y A289122 Cf. A289120, A289133, A288156, A004523, A289139.
%K A289122 nonn,easy
%O A289122 0,9
%A A289122 _Ralf Steiner_, Jun 25 2017