cp's OEIS Frontend

A211907 Number of lower triangular n X n arrays colored with integers 0 upwards introduced in row major order, with no element equal to any horizontal or vertical neighbor, and containing the value n(n+1)/2-4.

%I A211907 #6 Jun 02 2025 07:51:25
%S A211907 0,0,41,2385,55822,637721,4639742,24871596,106911695,388681117,
%T A211907 1238600816,3548005682,9306274551
%N A211907 Number of lower triangular n X n arrays colored with integers 0 upwards introduced in row major order, with no element equal to any horizontal or vertical neighbor, and containing the value n(n+1)/2-4.
%C A211907 Column 3 of A211910
%e A211907 Some solutions for n=4
%e A211907 ..0........0........0........0........0........0........0........0
%e A211907 ..1.2......1.2......1.0......1.2......1.2......1.0......1.2......1.0
%e A211907 ..3.4.5....0.3.2....2.3.4....3.4.2....3.4.3....2.3.4....3.1.4....2.1.3
%e A211907 ..6.3.0.6..4.5.3.6..1.0.5.6..0.3.5.6..4.5.2.6..5.2.6.5..5.6.3.4..1.4.5.6
%K A211907 nonn
%O A211907 1,3
%A A211907 _R. H. Hardin_ Apr 25 2012