A207069 Number of 2 X n 0..1 arrays avoiding 0 0 1 and 0 1 0 horizontally and 0 0 1 and 1 0 1 vertically.

4, 16, 36, 81, 196, 441, 961, 2116, 4624, 10000, 21609, 46656, 100489, 216225, 465124, 1000000, 2149156, 4618201, 9922500, 21316689, 45792289, 98366724, 211295296, 453860416, 974875729, 2093977600, 4497714225, 9660727521, 20750402500

Offset

1,1

Comments

Row 2 of A207068.

Links

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

Formula

Empirical: a(n) = 3*a(n-1) - 2*a(n-2) + 3*a(n-3) - 6*a(n-4) + 3*a(n-7) + a(n-8) - a(n-10).

Empirical g.f.: x*(4 + 4*x - 4*x^2 - 7*x^3 + x^4 + 3*x^5 + 3*x^6 + x^7 - x^8 - x^9) / ((1 - x)*(1 + x^2 - x^3)*(1 - x - x^3)*(1 - x - 2*x^2 - x^3)). - Colin Barker, Feb 17 2018

Example

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

Crossrefs

Sequence in context: A030179 A207025 A207170 * A207436 A189145 A005722

Adjacent sequences: A207066 A207067 A207068 * A207070 A207071 A207072

Keyword

nonn

Author

R. H. Hardin, Feb 14 2012

Status

approved