A207657 Number of nX4 0..1 arrays avoiding 0 0 0 and 1 1 1 horizontally and 0 0 1 and 1 0 0 vertically

10, 100, 292, 870, 2774, 9060, 30440, 103838, 359206, 1254128, 4412792, 15616086, 55522546, 198135096, 709186104, 2544574170, 9148317066, 32944585328, 118801548180, 428898598218, 1549885877794, 5605176866756, 20284633906700

Offset

1,1

Comments

Column 4 of A207661

Links

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

Formula

Empirical: a(n) = 8*a(n-1) -9*a(n-2) -67*a(n-3) +135*a(n-4) +215*a(n-5) -508*a(n-6) -375*a(n-7) +781*a(n-8) +426*a(n-9) -467*a(n-10) -263*a(n-11) +81*a(n-12) +51*a(n-13) -4*a(n-14) -3*a(n-15) for n>16

Example

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

Crossrefs

Sequence in context: A207348 A207770 A207897 * A305668 A262761 A134556

Adjacent sequences: A207654 A207655 A207656 * A207658 A207659 A207660

Keyword

nonn

Author

R. H. Hardin Feb 19 2012

Status

approved