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 A211365 #10 Jul 13 2012 17:33:04 %S A211365 1,2,10,6,36,186,24,168,1032,6936,120,960,6840,53040,462120,720,6480, %T A211365 52560,461520,4499280,48453840,5040,50400,458640,4495680,48449520, %U A211365 571404960,7321381200,40320,443520,4475520,48424320,571374720,7321345920 %N A211365 Array read by antidiagonals: T(m,n) = Sum(1<=i<=m) i * (2m+n-1-i)! %C A211365 Index numbers (compare A055089) of permutations like (2,4,6,...,1,3,5...). %H A211365 Tilman Piesk, <a href="/A211365/b211365.txt">Table of n, a(n) for n = 1..2016</a> %H A211365 Tilman Piesk, <a href="http://en.wikiversity.org/wiki/Inversion_%28discrete_mathematics%29#arrays1">Arrays of permutations</a> (Wikiversity) %e A211365 T(3,2) = Sum( 1 <= i <= 3 ) [ i * (7-i)! ] %e A211365 = 1*(7-1)! + 2*(7-2)! + 3*(7-3)! %e A211365 = 1*720 + 2*120 + 3*24 %e A211365 = 1032 %Y A211365 Cf. A055089. %K A211365 nonn,tabl %O A211365 1,2 %A A211365 _Tilman Piesk_, Jun 22 2012