A208394 Number of 3 X n 0..2 arrays with new values 0..2 introduced in row major order and no element equal to more than two of its immediate leftward or upward or right-upward antidiagonal neighbors.
5, 122, 3042, 76806, 1937736, 48890520, 1233536544, 31122868320, 785248636032, 19812294175104, 499876067713536, 12612173071468032, 318212692821854208, 8028697140386371584, 202568845385856983040, 5110933493125207056384
Offset: 1
Keywords
Examples
Some solutions for n=4: ..0..1..2..1....0..0..1..2....0..0..1..2....0..0..0..1....0..0..0..0 ..2..0..0..1....0..2..1..0....0..2..0..2....1..1..1..0....0..1..0..0 ..0..2..0..1....2..1..2..1....2..2..0..2....0..1..2..2....0..1..2..0
Links
- R. H. Hardin, Table of n, a(n) for n = 1..210
Crossrefs
Cf. A208392.
Formula
Empirical: a(n) = 22*a(n-1) + 80*a(n-2) + 40*a(n-3) - 48*a(n-4) for n>6.
Empirical g.f.: x*(5 + 12*x - 42*x^2 - 78*x^3 + 4*x^4 + 24*x^5) / ((1 + 2*x)*(1 - 24*x - 32*x^2 + 24*x^3)). - Colin Barker, Jul 02 2018
Comments