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 A262806 #16 Oct 09 2015 12:53:25 %S A262806 1,100,9101,91010000,901900901001,901900901001000000, %T A262806 901089109010900090010001,90108910901090009001000100000000, %U A262806 9010080101801008010090100900009000100001,90100801018010080100901009000090001000010000000000,900999901099900099901099900999901000901000900000900001000001 %N A262806 a(n) = A065447(n) / A002275(floor((n+1)/2)). %F A262806 a(n) = A065447(n) / A002275(floor((n+1)/2)). %F A262806 a(2*n) = a(2*n-1) * 10^(2*n). %e A262806 a(5) = 100111000011111 / 111 = 901900901001. %K A262806 nonn,base,easy %O A262806 1,2 %A A262806 _Max Alekseyev_, Oct 03 2015