A204644 Number of (n+1) X 2 0..1 arrays with column and row pair sums b(i,j)=a(i,j)+a(i,j-1) and c(i,j)=a(i,j)+a(i-1,j) nondecreasing in column and row directions, respectively.

8, 16, 28, 48, 80, 132, 216, 352, 572, 928, 1504, 2436, 3944, 6384, 10332, 16720, 27056, 43780, 70840, 114624, 185468, 300096, 485568, 785668, 1271240, 2056912, 3328156, 5385072, 8713232, 14098308, 22811544, 36909856, 59721404, 96631264, 156352672, 252983940

Offset: 1

Author

R. H. Hardin, Jan 17 2012

Keywords

• nonn

Examples

			Some solutions for n=5:
  0 1   0 1   0 0   0 0   0 1   0 0   1 0   0 0   0 0   0 0
  0 1   0 1   0 0   0 0   1 0   0 1   0 1   0 0   0 0   1 1
  1 0   0 1   0 0   0 0   0 1   0 1   1 0   0 1   0 0   1 1
  0 1   0 1   0 1   0 0   1 1   0 1   0 1   0 1   0 1   1 1
  0 1   1 0   1 0   0 0   1 1   0 1   1 0   0 1   1 1   1 1
  1 1   0 1   0 1   0 1   1 1   0 1   0 1   1 1   1 1   1 1
		

Links

• R. H. Hardin, Table of n, a(n) for n = 1..210
• Index entries for linear recurrences with constant coefficients, signature (2, 0, -1) (empirical).

Crossrefs

Column 1 of A204651.

Formula

Empirical: a(n) = 2*a(n-1) - a(n-3).

From the empirical recurrence, a(n) = 4*(Fibonacci(n + 3) - 1). - Ehren Metcalfe, Apr 04 2019