A207683 Number of 3 X n 0..1 arrays avoiding 0 0 0 and 1 0 1 horizontally and 0 0 1 and 1 1 1 vertically.

6, 36, 72, 164, 336, 702, 1488, 3164, 6612, 13916, 29532, 62032, 130548, 275904, 581196, 1223824, 2581620, 5442424, 11466060, 24172016, 50959908, 107395128, 226366524, 477188096, 1005780564, 2119935656, 4468615788, 9419000656

Offset

1,1

Comments

Row 3 of A207682.

Links

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

Formula

Empirical: a(n) = a(n-2) + 6*a(n-3) + 4*a(n-4) - 6*a(n-6) for n>8.

Empirical g.f.: 2*x*(3 + 18*x + 33*x^2 + 46*x^3 + 12*x^4 - 19*x^5 - 42*x^6 + 3*x^7) / (1 - x^2 - 6*x^3 - 4*x^4 + 6*x^6). - Colin Barker, Mar 05 2018

Example

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

Crossrefs

Cf. A207682.

Sequence in context: A208064 A207929 A171506 * A207509 A207846 A207840

Adjacent sequences: A207680 A207681 A207682 * A207684 A207685 A207686

Keyword

nonn

Author

R. H. Hardin, Feb 19 2012

Status

approved