A235541 - OEIS

%I #8 Mar 19 2018 10:28:10

%S 16,48,141,378,988,2482,6109,14712,34896,81612,188725,432046,980620,

%T 2208798,4941909,10990620,24311440,53516200,117285181,256007874,

%U 556755036,1206716778,2607303661,5617260448,12069653488,25869224292

%N Number of (n+1) X (1+1) 0..1 arrays with the sum of each 2 X 2 subblock two median terms lexicographically nondecreasing rowwise and columnwise.

%C Column 1 of A235548.

%H R. H. Hardin, <a href="/A235541/b235541.txt">Table of n, a(n) for n = 1..210</a>

%F Empirical: a(n) = 4*a(n-1) - 14*a(n-3) + 5*a(n-4) + 18*a(n-5) - 4*a(n-6) - 8*a(n-7).

%F Empirical g.f.: x*(16 - 16*x - 51*x^2 + 38*x^3 + 68*x^4 - 24*x^5 - 32*x^6) / ((1 - x)*(1 + x)^3*(1 - 2*x)^3). - _Colin Barker_, Mar 19 2018

%e Some solutions for n=5:

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

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

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

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

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

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

%Y Cf. A235548.

%K nonn

%O 1,1

%A _R. H. Hardin_, Jan 12 2014