A250693 - OEIS

%I #4 Nov 26 2014 20:02:08

%S 520,2920,13906,60508,249512,995624,3894542,15061244,57914756,

%T 222291368,853854042,3287692860,12701872800,49262782920,191821043814,

%U 749801489244,2941369935292,11575782602248,45685412767666,180742482085084

%N Number of (2+1)X(n+1) 0..3 arrays with nondecreasing x(i,j)-x(i,j-1) in the i direction and nondecreasing absolute value of x(i,j)-x(i-1,j) in the j direction

%C Row 2 of A250691

%H R. H. Hardin, <a href="/A250693/b250693.txt">Table of n, a(n) for n = 1..210</a>

%F Empirical: a(n) = 20*a(n-1) -175*a(n-2) +882*a(n-3) -2835*a(n-4) +6072*a(n-5) -8777*a(n-6) +8458*a(n-7) -5204*a(n-8) +1848*a(n-9) -288*a(n-10)

%e Some solutions for n=4

%e ..2..3..1..1..1....0..2..1..0..0....0..1..1..1..2....0..0..3..1..2

%e ..1..2..0..0..0....0..2..2..2..2....0..1..1..1..3....0..0..3..1..2

%e ..0..3..3..3..3....0..3..3..3..3....0..1..1..1..3....0..0..3..1..3

%K nonn

%O 1,1

%A _R. H. Hardin_, Nov 26 2014