A223459 - OEIS

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A223459

6X6X6 triangular graph without horizontal edges coloring a rectangular array: number of n X n 0..20 arrays where 0..20 label nodes of a graph with edges 0,1 0,2 1,3 1,4 2,4 2,5 3,6 3,7 4,7 4,8 5,8 5,9 6,10 6,11 7,11 7,12 8,12 8,13 9,13 9,14 10,15 10,16 11,16 11,17 12,17 12,18 13,18 13,19 14,19 14,20 and every array movement to a horizontal or vertical neighbor moves along an edge of this graph

%I #5 Dec 18 2015 18:18:31

%S 21,400,47100,31075684,116111266332,2412122721426324,

%T 280173531066504459408,180359138791051357960964956,

%U 646396187061902362932292802186560

%N 6X6X6 triangular graph without horizontal edges coloring a rectangular array: number of n X n 0..20 arrays where 0..20 label nodes of a graph with edges 0,1 0,2 1,3 1,4 2,4 2,5 3,6 3,7 4,7 4,8 5,8 5,9 6,10 6,11 7,11 7,12 8,12 8,13 9,13 9,14 10,15 10,16 11,16 11,17 12,17 12,18 13,18 13,19 14,19 14,20 and every array movement to a horizontal or vertical neighbor moves along an edge of this graph

%C Diagonal of A223467

%e Some solutions for n=3

%e ..6.11..6....8.13..8....7.12..7....7..4..1...12.18.12....1..0..2...14.19.13

%e .11..7.11...13..8..5....4..8..4....4..1..4...17.12..7....0..2..0....9.14..9

%e ..6.11..6....8.13..9....8..5..2....1..3..7...11.17.11....1..0..1...13..9.13

%K nonn

%O 1,1

%A _R. H. Hardin_ Mar 20 2013