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 A135989 #15 Aug 29 2016 12:00:59 %S A135989 3,9,105,201,207,303,309,405,501,507,603,609,705,801,807,903,909,1005, %T A135989 1101,1107,1203,1209,1305,1401,1407,1503,1509,1605,1701,1707,1803, %U A135989 1809,1905,2001,2007,2103,2109,2205,2301,2307,2403,2409,2505,2601,2607,2703 %N A135989 a(n) = 6*n + 3 + 90*floor((6*n+3)/10). %C A135989 All terms are divisible by 3. %F A135989 a(n) = a(n-1)+a(n-5)-a(n-6). - _Colin Barker_, Feb 02 2013 %F A135989 G.f.: 3*(31*x^5 +2*x^4 +32*x^3 +32*x^2 +2*x +1) / ((x -1)^2*(x^4 +x^3 +x^2 +x +1)). - _Colin Barker_, Feb 02 2013 %K A135989 nonn,easy %O A135989 0,1 %A A135989 _Stefano Maruelli_ and Paola Paoloni (robotec(AT)netsurf.it), Mar 02 2008 %E A135989 Edited by _Charles R Greathouse IV_, Nov 03 2009