A182293 - OEIS

%I #10 Oct 11 2014 02:13:50

%S 1,2,22,2418,4276864

%N Number of lower triangular n X n arrays of integers 0 upwards introduced in row major order, with each element unique in its row and column.

%e Some solutions for n=4:

%e ..0........0........0........0........0........0........0........0

%e ..1.2......1.2......1.0......1.2......1.2......1.2......1.2......1.0

%e ..3.4.1....3.4.5....2.3.4....3.0.4....3.4.5....3.1.4....3.4.5....2.3.4

%e ..5.3.4.2..5.1.4.3..5.2.0.1..4.5.3.6..5.6.4.2..2.5.3.4..6.5.7.0..5.6.3.2

%K nonn,more

%O 1,2

%A _R. H. Hardin_, Apr 24 2012