A221626 - OEIS

%I #4 Jan 21 2013 07:29:17

%S 1,5,453,85035,51149685,57614883627,130516916069715,

%T 492362067027383802,3063154239917651379537,28932140956374841410316707,

%U 405028623674958829496315433651,8040080740216333451541433497055002

%N Number of 4Xn arrays with each row a permutation of 1..n having at least as many downsteps as the preceding row

%C Row 4 of A221623

%H R. H. Hardin, <a href="/A221626/b221626.txt">Table of n, a(n) for n = 1..13</a>

%e Some solutions for n=3

%e ..2..3..1....1..3..2....1..2..3....2..3..1....2..1..3....1..2..3....2..3..1

%e ..2..3..1....2..1..3....1..2..3....1..3..2....3..1..2....1..2..3....2..3..1

%e ..2..3..1....2..3..1....3..1..2....2..1..3....3..1..2....1..3..2....3..1..2

%e ..1..3..2....2..3..1....2..1..3....3..1..2....2..3..1....2..1..3....1..3..2

%K nonn

%O 1,2

%A _R. H. Hardin_ Jan 21 2013