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 A160797 #7 Mar 30 2012 18:39:36 %S A160797 1,7,3,21,3,21,9,63,3,21,9,63,9,63,27,189,3,21,9,63,9,63,27,189,9,63, %T A160797 27,189,27,189,81,567,3,21,9,63,9,63,27,189,9,63,27,189,27,189,81,567, %U A160797 9,63,27,189,27,189,81,567,27,189,81,567,81 %N A160797 First differences of A160796. %Y A160797 Cf. A152980, A160796. %K A160797 nonn,less %O A160797 1,2 %A A160797 _Omar E. Pol_, Jun 13 2009 %E A160797 More terms from _Sean A. Irvine_, Mar 22 2011