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 A224291 #5 Apr 03 2013 11:55:54 %S A224291 0,0,0,0,1,11,60,270,1084,4028,14144,47577,154740,489728,1514786, %T A224291 4593118,13682374,40106060,115824376,329901232,927585696,2576685888, %U A224291 7076644480,19228648192,51725149184 %N A224291 Number of permutations of length n containing exactly 4 occurrences of 123 and 4 occurrences of 132. %H A224291 B. Nakamura, <a href="http://arxiv.org/abs/1301.5080">Approaches for enumerating permutations with a prescribed number of occurrences of patterns</a>, arXiv 1301.5080, 2013. %p A224291 # Programs can be obtained from author's personal website. %Y A224291 Cf. A000079, A001787, A001815, A046718, A001793. %K A224291 nonn %O A224291 1,6 %A A224291 _Brian Nakamura_, Apr 03 2013