A207551 Number of 3Xn 0..2 arrays avoiding the pattern z-2 z-1 z in any row, column, nw-to-se diagonal or ne-to-sw antidiagonal.

26, 676, 14974, 327518, 7169168, 156957792, 3434478282, 75148438711, 1644205521524, 35974053130024, 787081975249822, 17220673773304768, 376773189954832060, 8243464731968266960, 180359713794644968034

Offset: 1

Author

R. H. Hardin Feb 18 2012

Keywords

• nonn

Comments

Row 3 of A207550

Examples

			Some solutions for n=4
..1..2..0..2....2..2..2..2....2..0..2..1....1..1..1..2....0..2..2..0
..0..0..2..0....0..0..0..0....2..0..0..0....1..1..1..1....0..0..0..0
..1..2..2..2....1..2..2..1....0..2..0..1....2..1..2..2....0..2..1..0
		

Links

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

Formula

Empirical: a(n) = 26*a(n-1) -16*a(n-2) -1876*a(n-3) +4292*a(n-4) +30528*a(n-5) -63675*a(n-6) -102108*a(n-7) -7290*a(n-8) -8276*a(n-9) +1540054*a(n-10) -8712728*a(n-11) [phone]*a(n-12) [phone]*a(n-13) -83820630*a(n-14) -96411600*a(n-15) -100641171*a(n-16) -89584866*a(n-17) [phone]*a(n-18) [phone]*a(n-19) [phone]*a(n-20) [phone]*a(n-21) -134950279*a(n-22) -86365344*a(n-23) +5316948*a(n-24) +71280*a(n-25) for n>26