A217505 - OEIS

%I #6 Jan 19 2025 14:27:01

%S 1,10,306,34489,14162520,21101953059,113688398105827

%N Number of triangular n X n X n arrays of occupancy after each element either stays or moves to some neighbor and with no occupancy greater than 3.

%e Some solutions for n=4:

%e .....0........0........2........0........0........0........2........1

%e ....2.3......2.0......0.0......1.1......0.3......0.1......2.0......3.0

%e ...2.0.2....0.2.0....3.1.0....2.0.2....1.3.3....0.1.2....2.0.0....1.0.2

%e ..0.0.1.0..2.0.2.2..2.1.0.1..1.3.0.0..0.0.0.0..3.2.1.0..0.2.1.1..1.2.0.0

%Y Column 3 of A217510.

%K nonn,more

%O 1,2

%A _R. H. Hardin_, Oct 05 2012