A165371 Number of slanted n X n (i=1..n)X(j=i..n+i-1) 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, 40, 1409, 63740, 5386897, 948440084, 397609974217

Offset

2,2

Links

Table of n, a(n) for n=2..8.

Example

Some solutions for n=4
...1.1.1.2.........1.1.2.2.........1.1.1.2.........1.1.1.2......
.....1.1.4.4.........2.2.2.4.........1.3.2.2.........1.3.2.2....
.......1.1.4.4.........2.3.4.4.........3.3.3.3.........3.3.2.2..
.........3.4.4.4.........3.4.4.4.........3.3.3.4.........3.2.4.4
------
...1.1.2.2.........1.2.2.2.........1.4.4.2.........1.1.1.2......
.....1.1.4.4.........2.2.4.4.........4.4.4.4.........2.2.2.2....
.......4.4.4.4.........2.4.4.4.........4.4.4.4.........3.3.3.3..
.........3.4.4.4.........3.4.4.4.........3.3.4.4.........3.3.4.4
------
...1.1.2.2.........1.1.2.2.........1.1.1.2.........1.1.1.2......
.....1.2.2.2.........1.2.2.2.........1.1.1.1.........1.1.2.2....
.......2.3.2.2.........3.3.3.4.........3.3.3.4.........1.2.2.2..
.........3.2.2.4.........3.4.4.4.........3.3.4.4.........3.3.2.4

Crossrefs

Sequence in context: A188253 A049396 A135644 * A162877 A163223 A163669

Adjacent sequences: A165368 A165369 A165370 * A165372 A165373 A165374

Keyword

nonn

Author

R. H. Hardin Sep 17 2009

Status

approved