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 A133646 #10 Jan 02 2024 08:55:25
%S A133646 1,5,50,400,3500,29500,252500,2147500,18312500,155987500,1329312500,
%T A133646 11326187500,96510312500,822337187500,7006995312500,59705092187500,
%U A133646 508735320312500,4334829367187500,36936206445312500,314725913242187500
%N A133646 a(n)=5*a(n-1)+30*a(n-2) for n>=3, a(0)=1, a(1)=5, a(2)=50 .
%H A133646 <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (5, 30).
%F A133646 G.f.: (1-5*x^2)/(1-5*x-30*x^2) . a(n) = Sum_{k, 0<=k<=n}A122950(n,k)*5^k .
%K A133646 easy,nonn
%O A133646 0,2
%A A133646 _Philippe Deléham_, Dec 31 2007