A204034 Number of (n+1)X4 0..1 arrays with the sums of 2X2 subblocks nondecreasing rightwards and downwards

121, 603, 2928, 10505, 37642, 111578, 330509, 863435, 2254026, 5394662, 12906149, 29037224, 65337510, 140736855, 303340170, 634000207, 1326522462, 2717180447, 5573314419, 11270539628, 22825534613, 45808619416, 92067615036, 184020632660

Offset

1,1

Comments

Column 3 of A204039

Links

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

Formula

Empirical: a(n) = 4*a(n-1) +20*a(n-2) -98*a(n-3) -168*a(n-4) +1122*a(n-5) +674*a(n-6) -7970*a(n-7) -205*a(n-8) +39322*a(n-9) -13326*a(n-10) -142896*a(n-11) +86380*a(n-12) +395612*a(n-13) -325028*a(n-14) -850708*a(n-15) +867429*a(n-16) +1433880*a(n-17) -1752520*a(n-18) -1894178*a(n-19) +2759240*a(n-20) +1938970*a(n-21) -3430470*a(n-22) -1491450*a(n-23) +3380665*a(n-24) +795530*a(n-25) -2631230*a(n-26) -214060*a(n-27) +1599540*a(n-28) -65400*a(n-29) -744088*a(n-30) +104272*a(n-31) +255920*a(n-32) -56864*a(n-33) -61344*a(n-34) +17856*a(n-35) +9152*a(n-36) -3200*a(n-37) -640*a(n-38) +256*a(n-39)

Example

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

Crossrefs

Sequence in context: A183448 A296127 A307798 * A183885 A036306 A014749

Adjacent sequences: A204031 A204032 A204033 * A204035 A204036 A204037

Keyword

nonn

Author

R. H. Hardin Jan 09 2012

Status

approved