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 A180153 #7 Nov 03 2016 06:10:47 %S A180153 1,121,12421,1246421,124696421,12470296421,1247037296421, %T A180153 124703817296421,12470382717296421,1247038282717296421, %U A180153 124703828392717296421,12470382840592717296421,1247038284073592717296421,124703828407513592717296421,12470382840753013592717296421 %N A180153 a(n) = 10*a(n-1) + A109242(n). %H A180153 Colin Barker, <a href="/A180153/b180153.txt">Table of n, a(n) for n = 1..500</a> %H A180153 <a href="/index/Rec#order_04">Index entries for linear recurrences with constant coefficients</a>, signature (121,-2220,12100,-10000). %F A180153 From _Colin Barker_, Oct 03 2015: (Start) %F A180153 a(n) = 121*a(n-1)-2220*a(n-2)+12100*a(n-3)-10000*a(n-4) for n>4. %F A180153 G.f.: x / ((x-1)*(10*x-1)^2*(100*x-1)). %F A180153 (End) %o A180153 (PARI) Vec(x / ((x-1)*(10*x-1)^2*(100*x-1)) + O(x^30)) \\ _Colin Barker_, Oct 03 2015 %Y A180153 Cf. A109242, A000292, A002620, A059259, A094028. %K A180153 nonn,easy %O A180153 1,2 %A A180153 _Mark Dols_, Aug 13 2010