A207764 Number of 4Xn 0..1 arrays avoiding 0 0 0 and 1 0 1 horizontally and 0 1 1 and 1 0 1 vertically.

9, 81, 193, 663, 1664, 4018, 11509, 30943, 79178, 213444, 574517, 1510235, 4016905, 10742833, 28499913, 75702647, 201719465, 536397481, 1425655190, 3793651190, 10091485607, 26833849671, 71376964346, 189863830540, 504956635718

Offset: 1

Author

R. H. Hardin Feb 19 2012

Keywords

• nonn

Comments

Row 4 of A207762

Examples

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

Links

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

Formula

Empirical: a(n) = 3*a(n-1) -3*a(n-2) +15*a(n-3) -28*a(n-4) +16*a(n-5) -51*a(n-6) +83*a(n-7) -21*a(n-8) +65*a(n-9) -150*a(n-10) +64*a(n-11) -54*a(n-12) +132*a(n-13) -76*a(n-14) +26*a(n-15) -40*a(n-16) +20*a(n-17) for n>19