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 A196687 #9 May 01 2013 21:13:46 %S A196687 1,4,24,336,5520,203040,7025760,510370560,30163311360,3577017024000, %T A196687 319851801561600,55850407258060800,7021439018770176000, %U A196687 1692163531361176473600,284409062346887622144000,90395009213694143422464000,19571060809440210728706048000,7929132907666579072319471616000 %N A196687 n!*A062868(n). %C A196687 Let p = (p1..pn) and q = (q1..qn) be two random permutations of (1..n); call the pair (p,q) balanced if the number of i with pi > qi is the same as the number of i with pi < qi. Then a(n) is the number of balanced pairs. %Y A196687 Cf. A062868, A196688. %K A196687 nonn %O A196687 1,2 %A A196687 Jan Lakota, Oct 04 2011 %E A196687 a(1)-a(6) computed by Jan Lakota; extended by _N. J. A. Sloane_, Oct 04 2011