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 A230553 #13 Oct 28 2013 13:30:06 %S A230553 1,1,2,4,10,24,62,156,406,1040,2714,7012,18322,47560,124358,323708, %T A230553 846766,2208032,5777330,15082372,39469786 %N A230553 Number of involutions avoiding the pattern 1342. %H A230553 Miklós Bóna, Cheyne Homberger, Jay Pantone, and Vince Vatter, <a href="http://arxiv.org/abs/1310.7003">Pattern-avoiding involutions: exact and asymptotic enumeration</a>, arxiv:1310.7003, 2013. %e A230553 Of the 26 involutions of length 5, only 14523 and 15342 contain the pattern 1342, so a(5) = 24. %Y A230553 Cf. A000085, A001006, A121704, A230551-A230556. %K A230553 nonn %O A230553 0,3 %A A230553 _Cheyne Homberger_, Oct 23 2013