cp's OEIS Frontend

A250685 Number of (n+1)X(2+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.

%I A250685 #6 Jul 23 2025 12:41:30
%S A250685 543,2920,15246,76320,362241,1647460,7249825,31113316,131014715,
%T A250685 543845812,2233368847,9098214240,36844025643,148553970588,
%U A250685 597082293823,2394504059784,9587995012203,38352450171812,153311305422383
%N A250685 Number of (n+1)X(2+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 A250685 Column 2 of A250691
%H A250685 R. H. Hardin, <a href="/A250685/b250685.txt">Table of n, a(n) for n = 1..210</a>
%F A250685 Empirical: a(n) = 27*a(n-1) -331*a(n-2) +2439*a(n-3) -12049*a(n-4) +42129*a(n-5) -107225*a(n-6) +201069*a(n-7) -277706*a(n-8) +278928*a(n-9) -197984*a(n-10) +94032*a(n-11) -26784*a(n-12) +3456*a(n-13) for n>17
%e A250685 Some solutions for n=4
%e A250685 ..1..1..1....2..2..0....3..2..2....3..2..1....2..2..0....2..1..0....3..0..1
%e A250685 ..1..1..2....3..3..2....3..2..2....3..3..3....3..3..2....2..3..3....3..0..1
%e A250685 ..2..2..3....2..2..3....3..2..2....3..3..3....1..1..0....2..3..3....3..0..2
%e A250685 ..0..0..1....0..0..1....3..3..3....0..0..0....0..0..2....0..1..1....3..0..2
%e A250685 ..0..1..3....0..0..1....3..3..3....2..2..3....0..0..2....1..3..3....2..1..3
%K A250685 nonn
%O A250685 1,1
%A A250685 _R. H. Hardin_, Nov 26 2014