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 A068533 #7 Aug 14 2015 08:38:00 %S A068533 1,61,446581,47864301941221,1099675872153778794555007944901, %T A068533 1160915542845287082257685451398396234242229540362376748831753861, %U A068533 2587631803429953767431812922335511171298614788064511166728057883038770884444505265048062877435638536484571643805442456022573810181 %N A068533 a(n) = (11^(2^n)-1)/2^(n+2)/15. %K A068533 easy,nonn %O A068533 1,2 %A A068533 _Benoit Cloitre_, Mar 22 2002