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 A089838 #6 Mar 31 2012 14:02:17 %S A089838 1,0,14,15,16,13,12,21,18,17,19,20,6,5,2,3,4,9,8,10,11,7,145,146,147, %T A089838 144,143,149,148,153,152,151,150,156,157,154,155,159,158,140,139,141, %U A089838 142,138,137,168,169,170,167,166,172,171,176,175,174,173,179,180,177 %N A089838 Involution of nonnegative integers: row 1 of A089839. %H A089838 A. Karttunen, <a href="/A089839/a089839.c.txt">C-program for computing the initial terms of this sequence</a> %H A089838 <a href="/index/Per#IntegerPermutation">Index entries for sequences that are permutations of the natural numbers</a> %Y A089838 Cf. A089837, A089843. %K A089838 nonn %O A089838 0,3 %A A089838 _Antti Karttunen_, Dec 05 2003