login

Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).

Array read by antidiagonals: T(m,n) = m*(m+n-1)! + Sum( n <= i <= m+n-2 ) i!
2

%I #14 May 11 2013 11:01:15

%S 1,2,5,6,14,21,24,54,80,105,120,264,390,512,633,720,1560,2304,3030,

%T 3752,4473,5040,10800,15960,21024,26070,31112,36153,40320,85680,

%U 126720,167160,207504,247830,288152,328473,362880,766080,1134000

%N Array read by antidiagonals: T(m,n) = m*(m+n-1)! + Sum( n <= i <= m+n-2 ) i!

%C Index numbers (compare A055089) of transpositions.

%H Tilman Piesk, <a href="/A211369/b211369.txt">Table of n, a(n) for n = 1..2016</a>

%H Tilman Piesk, <a href="http://en.wikiversity.org/wiki/Inversion_%28discrete_mathematics%29#arrays3">Arrays of permutations</a> (Wikiversity)

%F T(m,1) = A001563(m) + A007489(m-1). - _R. J. Mathar_, May 11 2013

%e T(3,2) = 3*4! + Sum( 2 <= i <= 3 ) i!

%e = 3*4! + 2! + 3!

%e = 3*24 + 2 + 6 = 80.

%e The array starts:

%e 1, 2, 6, 24, 120,...

%e 5, 14, 54, 264, 1560,...

%e 21, 80, 390, 2304, 15960,...

%e 105, 512, 3030, 21024,167160,...

%e 633, 3752, 26070,207504,1860600,...

%p A211369 := proc(m,n)

%p m*(m+n-1)!+add(i!,i=n..m+n-2) ;

%p end proc: # _R. J. Mathar_, May 10 2013

%Y Cf. A055089, A000142 (row 1), A052649 (row 2)

%K nonn,tabl

%O 1,2

%A _Tilman Piesk_, Jul 07 2012