A207070 Number of 3Xn 0..1 arrays avoiding 0 0 1 and 0 1 0 horizontally and 0 0 1 and 1 0 1 vertically

6, 36, 102, 288, 896, 2499, 6634, 17848, 47192, 122200, 315315, 809784, 2063670, 5238225, 13261490, 33465000, 84237826, 211676500, 531027000, 1330245423, 3328592562, 8320844952, 20782671568, 51871277456, 129387019195, 322571437760

Offset

1,1

Comments

Row 3 of A207068

Links

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

Formula

Empirical: a(n) = 5*a(n-1) -9*a(n-2) +21*a(n-3) -56*a(n-4) +64*a(n-5) -89*a(n-6) +192*a(n-7) -119*a(n-8) +117*a(n-9) -305*a(n-10) +46*a(n-11) -64*a(n-12) +323*a(n-13) +39*a(n-14) +36*a(n-15) -228*a(n-16) -56*a(n-17) -4*a(n-18) +80*a(n-19) +24*a(n-20) -16*a(n-22)

Example

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

Crossrefs

Sequence in context: A207961 A207243 A207237 * A207118 A207704 A207495

Adjacent sequences: A207067 A207068 A207069 * A207071 A207072 A207073

Keyword

nonn

Author

R. H. Hardin Feb 14 2012

Status

approved