A164748 Number of n X n 1..4 arrays with all 1s connected, all 2s connected, all 3s connected, all 4s connected, 1 in the upper left corner, 2 in the upper right corner, 3 in the lower left corner, and 4 in the lower right corner

1, 108, 8181, 920072, 204261981

Offset

2,2

Links

Table of n, a(n) for n=2..6.

Example

Some solutions for n=4
...1.1.1.2...1.4.2.2...1.1.2.2...1.1.2.2...1.1.2.2...1.1.1.2...1.1.1.2
...1.3.3.3...1.4.4.4...1.1.1.1...1.1.2.2...4.2.2.2...3.3.1.4...1.1.2.2
...3.3.3.3...1.1.4.4...3.1.3.4...3.2.2.2...4.4.4.2...3.4.4.4...2.2.2.4
...3.4.4.4...3.3.4.4...3.3.3.4...3.3.4.4...3.4.4.4...3.4.4.4...3.3.2.4
------
...1.4.2.2...1.1.2.2...1.1.2.2...1.1.2.2...1.1.4.2...1.3.2.2...1.1.1.2
...4.4.4.4...3.1.1.1...1.1.1.4...1.4.4.4...4.4.4.2...3.3.2.2...1.1.1.1
...3.3.3.4...3.3.1.4...3.1.4.4...3.4.3.4...4.4.4.4...3.3.3.3...1.3.4.4
...3.3.3.4...3.3.3.4...3.3.3.4...3.3.3.4...3.3.3.4...3.3.4.4...3.3.4.4

Crossrefs

Sequence in context: A299857 A132053 A273439 * A269093 A113853 A209043

Adjacent sequences: A164745 A164746 A164747 * A164749 A164750 A164751

Keyword

nonn

Author

R. H. Hardin Aug 24 2009

Status

approved