A173279 - OEIS

%I #5 Mar 30 2012 17:40:17

%S 1,1,2,1,6,1,24,2,1,120,6,1,720,24,2,1,5040,120,6,1,40320,720,24,2,1,

%T 362880,5040,120,6,1,3628800,40320,720,24,2,1,39916800,362880,5040,

%U 120,6,1,479001600,3628800,40320,720,24,2,1,6227020800,39916800,362880,5040,120,6,1,87178291200

%N Irregular triangle read by rows: M(n,k) = (n-2*k)!, k=0..floor(n/2).

%C In the limit as j-> infinity, the power M^j approaches the limit described in A173280.

%C Row sums: sum_{k=0..n/2} M(n,k) = A136580(n).

%e Triangle starts in row n=0 as:

%e 1;

%e 1;

%e 2, 1;

%e 6, 1;

%e 24, 2, 1;

%e 120, 6, 1;

%e 720, 24, 2, 1;

%e 5040, 120, 6, 1;

%e 40320, 720, 24, 2, 1;

%e 362880, 5040, 120, 6, 1;

%e 3628800, 40320, 720, 24, 2, 1;

%e 39916800, 362880, 5040, 120, 6, 1;

%e 479001600, 3628800, 40320, 720, 24, 2, 1;

%e ...

%p A173279 := proc(n,k) factorial(n-2*k) ; end proc: seq(seq(A173279(n,k),k=0..floor(n/2)),n=0..20) ; # _R. J. Mathar_, Feb 22 2010

%Y Cf. A000142, A136580, A173280

%K nonn,tabf

%O 0,3

%A _Gary W. Adamson_, Feb 14 2010

%E keyword tabl replaced by tabf, _R. J. Mathar_, Feb 22 2010