A182403 - OEIS

%I #5 Dec 18 2015 18:17:27

%S 1,1,5,463,1092208,87637302208

%N Number of lower triangular n X n arrays colored with integers 0 upwards introduced in row major order, with no element equal to any element within a city block distance of two

%e Some solutions for n=4

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

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

%e ..3.0.4....3.4.5....3.4.0....3.0.4....3.4.0....3.0.4....3.4.5....3.4.5

%e ..4.5.6.0..6.7.1.3..5.6.7.8..5.1.3.5..5.6.7.5..2.5.1.2..6.7.3.0..5.6.3.0

%K nonn

%O 1,3

%A _R. H. Hardin_ Apr 27 2012