login

Reminder: The OEIS is hiring a new managing editor, and the application deadline is January 26.

Number of slanted 5Xn (i=1..5)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
0

%I #3 Mar 31 2012 12:35:35

%S 7,168,4569,63740,755947,7834644,74493401,661071448,5551999772,

%T 44577303412

%N Number of slanted 5Xn (i=1..5)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

%e Some solutions for n=3

%e ...1.2.2...........1.1.2...........1.1.2...........1.1.2........

%e .....2.2.2...........1.1.1...........1.2.4...........1.1.1......

%e .......2.2.2...........1.3.3...........4.4.4...........1.4.4....

%e .........2.3.4...........3.3.3...........4.4.4...........4.4.4..

%e ...........3.4.4...........3.4.4...........3.4.4...........3.4.4

%e ------

%e ...1.1.2...........1.1.2...........1.1.2...........1.1.2........

%e .....1.2.2...........2.2.2...........1.1.1...........1.1.1......

%e .......2.2.3...........2.2.3...........1.1.1...........1.1.3....

%e .........2.3.4...........3.3.4...........1.3.3...........1.3.4..

%e ...........3.4.4...........3.4.4...........3.4.4...........3.4.4

%e ------

%e ...1.3.2...........1.1.2...........1.2.2...........1.1.2........

%e .....3.3.3...........1.1.1...........2.2.2...........1.1.1......

%e .......3.3.3...........3.3.3...........4.4.4...........1.1.1....

%e .........3.3.3...........3.3.4...........4.4.4...........4.4.4..

%e ...........3.4.4...........3.4.4...........3.4.4...........3.4.4

%K nonn

%O 2,1

%A _R. H. Hardin_ Sep 17 2009