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

1,2

Comments

Column 3 of A206396.

Links

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

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

Example

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

Crossrefs

Cf. A206396.

Sequence in context: A369102 A124554 A321586 * A368968 A369511 A228966

Adjacent sequences: A206388 A206389 A206390 * A206392 A206393 A206394

Keyword

nonn

Author

R. H. Hardin, Feb 07 2012

Status

approved