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 A211366 #12 Feb 02 2025 13:29:44 %S A211366 1,2,13,6,50,373,24,246,2210,20533,120,1464,15366,163490,1834933,720, %T A211366 10200,122424,1466886,18307490,241335733,5040,81360,1098840,14637624, %U A211366 201050886,2892317090,43830481333,40320,730800,10967760,160766040 %N A211366 Array read by antidiagonals: T(m,n) = Sum(1<=i<=m) i * ( n + 2(i-1) )! %C A211366 Index numbers (compare A055089) of permutations like (n,1, n+1,2, n+2,3, ...). %H A211366 Tilman Piesk, <a href="/A211366/b211366.txt">Table of n, a(n) for n = 1..2016</a> %H A211366 Tilman Piesk, <a href="http://en.wikiversity.org/wiki/Inversion_%28discrete_mathematics%29#arrays1">Arrays of permutations</a> (Wikiversity) %e A211366 T(3,2) = Sum( 1 <= i <= 3 ) i * ( 2 + 2(i-1) )! %e A211366 = 1*(2+0)! + 2*(2+2)! + 3*(2+4)! %e A211366 = 1*2 + 2*24 + 3*720 %e A211366 = 2210 %o A211366 (MATLAB) % See Links section (the Wikiversity page). %Y A211366 Cf. A055089. %K A211366 nonn,tabl %O A211366 1,2 %A A211366 _Tilman Piesk_, Jul 07 2012