A181219 Number of n X 3 binary matrices with no three 1's adjacent in a line horizontally, vertically, diagonally or antidiagonally.

7, 49, 230, 1209, 6475, 34020, 179097, 944514, 4978956, 26241679, 138316703, 729070278, 3842881010, 20255521442, 106765644778, 562755120940, 2966245831625, 15634892911279, 82410528967137, 434380653636920, 2289592784455038, 12068297948426911, 63611230851907732, 335290751434945266

Offset

1,1

Links

R. H. Hardin, Table of n, a(n) for n=1..350

Formula

Empirical: a(n) = 2*a(n-1)+8*a(n-2)+38*a(n-3)+51*a(n-4)+41*a(n-5)-48*a(n-6)-88*a(n-7)-4*a(n-8)-8*a(n-9)-15*a(n-10)+14*a(n-11)-7*a(n-12)+a(n-13)-2*a(n-14).

Example

Some avoided solutions for 4 X 3:
..1..0..0....1..1..0....1..0..0....1..0..0....0..0..1....0..0..0....0..0..1
..0..1..0....0..1..0....0..0..1....0..1..0....0..1..0....0..0..0....0..1..0
..0..0..1....0..0..1....0..1..0....0..0..1....1..0..1....0..0..1....1..0..0
..0..1..0....0..0..0....1..0..0....1..0..0....0..0..0....1..1..1....0..0..1

Crossrefs

Column 3 of A181224.

Sequence in context: A188517 A206878 A206780 * A141783 A181479 A223842

Adjacent sequences: A181216 A181217 A181218 * A181220 A181221 A181222

Keyword

nonn

Author

R. H. Hardin, Oct 10 2010

Status

approved