A206391 Number of n X 3 0..5 arrays with no element equal to another within a city block distance of two, and new values 0..5 introduced in row major order.

1, 4, 26, 206, 1592, 12428, 96632, 752552, 5856992, 45595664, 354918176, 2762807264, 21506309504, 167411006144, 1303169775488, 10144214859392, 78965192918528, 614685592164608, 4784872150020608, 37246687385693696

Offset: 1

Author

R. H. Hardin, Feb 07 2012

Keywords

• nonn

Comments

Column 3 of A206396.

Examples

			Some solutions for n=4:
  0 1 2    0 1 2    0 1 2    0 1 2    0 1 2    0 1 2    0 1 2
  3 4 5    3 4 5    2 3 4    2 3 0    2 3 4    3 4 5    2 3 0
  5 0 1    1 0 3    4 5 1    4 5 1    1 5 0    1 0 3    1 4 5
  4 3 2    2 5 1    3 2 0    0 2 4    4 2 3    4 5 1    5 0 1
		

Links

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

Crossrefs

Cf. A206396.

Formula

Empirical: a(n) = 6*a(n-1) + 18*a(n-2) - 32*a(n-3) for n>5.

Empirical g.f.: x*(1 - 2*x - 16*x^2 + 10*x^3 + 16*x^4) / (1 - 6*x - 18*x^2 + 32*x^3). - Colin Barker, Jun 16 2018