A177191 - OEIS

%I #4 Jul 22 2012 16:38:32

%S 1,6,60,884,17520,439962,13421632,482342856,19956724992,934078894910,

%T 48784858450944,2812154505890556,177324556062404608,

%U 12140949539956154946,896952532589585448960,71119465538136504762128

%N Determinant of the n X n matrix whose element (r,c) is n for r = c, is -n for c>r, and 1 for c< r.

%F a(n) = ( (2n)^n+n*(n-1)^n ) /(n+1).

%e a(5) = determinant of the (5 X 5) matrix = 17520.

%e [ 5 -5 -5 -5 -5 ]

%e [ 1 5 -5 -5 -5 ]

%e [ 1 1 5 -5 -5 ]

%e [ 1 1 1 5 -5 ]

%e [ 1 1 1 1 5 ]

%p A177191 := proc(n)

%p     ((2*n)^n+n*(n-1)^n)/(n+1) ;

%p end proc:

%K nonn

%O 1,2

%A _Michel Lagneau_, May 04 2010