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 A196688 #11 May 01 2013 21:13:46 %S A196688 0,0,6,120,4440,157680,9187920,557665920,50759291520,4795586208000, %T A196688 636749560339200,86796062772249600,15877174512431232000, %U A196688 2953945462595410483200,712801595188655900928000,173684063741850454560768000,53471242848053479728254976000,16530628080065352033845256192000 %N A196688 ((n!)^2-A196687(n))/2. %C A196688 Let p = (p1..pn) and q = (q1..qn) be two random permutations of (1..n); call the pair (p,q) positive if the number of i with pi > qi is greater than the number of i with pi < qi. Then a(n) is the number of positive pairs. %Y A196688 Cf. A062868, A196687. Equals n!*A179567(n). %K A196688 nonn %O A196688 1,3 %A A196688 Jan Lakota, Oct 04 2011 %E A196688 a(1)-a(6) computed by Jan Lakota; extended by _N. J. A. Sloane_, Oct 04 2011