A207704 Number of 3Xn 0..1 arrays avoiding 0 0 0 and 0 1 0 horizontally and 0 0 1 and 1 1 0 vertically.

6, 36, 102, 289, 1071, 3969, 13230, 44100, 153090, 531441, 1815939, 6205081, 21332924, 73342096, 251550372, 862773129, 2961885201, 10168100569, 34894442176, 119749218304, 411007092416, 1410671672089, 4841491994817

Offset: 1

Author

R. H. Hardin Feb 19 2012

Keywords

• nonn

Comments

Row 3 of A207703

Examples

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

Links

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

Formula

Empirical: a(n) = 2*a(n-1) +10*a(n-3) +25*a(n-4) -2*a(n-5) +4*a(n-6) -28*a(n-7) -68*a(n-8) -2*a(n-9) +4*a(n-10) +10*a(n-11) +25*a(n-12) +2*a(n-13) -a(n-16)