A203184 - OEIS

%I #10 Feb 16 2018 11:11:56

%S 1,5,25,95,325,1121,3985,14288,50995,181336,644721,2294193,8166441,

%T 29066618,103444256,368138471,1310164527,4662787112,16594519920,

%U 59058487061,210183969235,748026706926,2662163892493,9474416502527

%N Number of nX1 0..4 arrays with every nonzero element less than or equal to some horizontal or vertical neighbor

%C Column 1 of A203191

%H R. H. Hardin, <a href="/A203184/b203184.txt">Table of n, a(n) for n = 1..210</a>

%F Empirical: a(n) = 5*a(n-1) -10*a(n-2) +20*a(n-3) -15*a(n-4) +21*a(n-5) -7*a(n-6) +8*a(n-7) -a(n-8) +a(n-9).

%F Empirical g.f.: -x*(1+x^2)*(x^6+6*x^4+9*x^2+1) / ( -1+5*x-10*x^2+20*x^3-15*x^4+21*x^5-7*x^6+8*x^7-x^8+x^9 ). - _R. J. Mathar_, Jul 02 2013

%e Some solutions for n=4

%e ..2....0....4....0....4....0....2....4....0....0....2....1....0....1....3....2

%e ..2....1....4....4....4....1....2....4....3....4....4....3....1....2....3....2

%e ..1....2....1....4....4....4....1....1....4....4....4....4....4....2....2....3

%e ..0....2....1....4....4....4....0....0....4....4....4....4....4....0....0....3

%K nonn

%O 1,2

%A _R. H. Hardin_, Dec 30 2011