A204033 Number of (n+1)X3 0..1 arrays with the sums of 2X2 subblocks nondecreasing rightwards and downwards.

44, 164, 603, 1758, 5130, 13040, 33223, 77574, 181559, 401370, 889157, 1896644, 4052667, 8444892, 17621165, 36165014, 74299430, 151007392, 307137335, 620376066, 1253727656, 2522563936, 5077320907, 10191401694, 20461362545

Offset: 1

Author

R. H. Hardin Jan 09 2012

Keywords

• nonn

Comments

Column 2 of A204039

Examples

			Some solutions for n=4
..1..1..0....1..1..0....1..1..1....1..0..1....0..0..1....1..0..0....1..1..1
..0..1..1....0..1..1....0..1..0....0..0..0....1..1..0....0..1..1....0..1..1
..1..1..1....1..1..1....1..1..1....0..1..1....0..1..1....1..1..0....1..1..1
..0..1..1....0..1..1....1..1..1....0..1..0....1..1..1....0..1..1....0..1..1
..1..1..1....1..1..1....1..1..1....1..1..1....1..1..1....1..1..0....1..1..1
		

Links

• R. H. Hardin, Table of n, a(n) for n = 1..210

Formula

Empirical: a(n) = 4*a(n-1) +8*a(n-2) -50*a(n-3) -9*a(n-4) +270*a(n-5) -128*a(n-6) -820*a(n-7) +709*a(n-8) +1520*a(n-9) -1824*a(n-10) -1722*a(n-11) +2797*a(n-12) +1070*a(n-13) -2696*a(n-14) -160*a(n-15) +1608*a(n-16) -240*a(n-17) -544*a(n-18) +160*a(n-19) +80*a(n-20) -32*a(n-21)