cp's OEIS Frontend

A250730 Number of (1+1)X(n+1) 0..1 arrays with nondecreasing x(i,j)+x(i,j-1) in the i direction and nondecreasing min(x(i,j),x(i-1,j)) in the j direction.

%I A250730 #8 Jul 23 2025 12:44:47
%S A250730 9,22,50,114,257,579,1302,2927,6578,14782,33216,74637,167709,376840,
%T A250730 846753,1902638,4275190,9606266,21585085,48501247,108981314,244878791,
%U A250730 550237650,1236372778,2778104416,6242343961,14026419561,31517078668
%N A250730 Number of (1+1)X(n+1) 0..1 arrays with nondecreasing x(i,j)+x(i,j-1) in the i direction and nondecreasing min(x(i,j),x(i-1,j)) in the j direction.
%C A250730 Row 1 of A250729
%H A250730 R. H. Hardin, <a href="/A250730/b250730.txt">Table of n, a(n) for n = 1..210</a>
%F A250730 Empirical: a(n) = 3*a(n-1) -a(n-2) -2*a(n-3) +a(n-4).
%F A250730 Empirical: G.f. x*( -9+5*x+7*x^2-4*x^3 ) / ( (x-1)*(x^3-x^2-2*x+1) ). - _R. J. Mathar_, Nov 27 2014
%e A250730 Some solutions for n=4
%e A250730 ..0..0..0..1..1....1..0..1..0..1....0..1..0..0..0....1..0..1..0..0
%e A250730 ..1..1..0..1..1....0..1..0..1..0....1..0..1..0..1....0..1..0..1..0
%K A250730 nonn
%O A250730 1,1
%A A250730 _R. H. Hardin_, Nov 27 2014