%I #3 Mar 18 2016 08:00:49
%S 0,21,1137,132474,34889103,22383193638,35714928884139,
%T 144182981347081503,1486449414781831854123,39397028534591054436055983,
%U 2696910972157269626108160017520,478461426234650496975341723139740316
%N Number of nXnXn triangular 0..3 arrays with some element plus some adjacent element totalling 3+1 exactly once.
%C Column 3 of A270509.
%e Some solutions for n=4
%e .....3........1........0........0........0........2........0........0
%e ....0.3......2.0......1.1......2.1......1.1......0.2......0.0......0.0
%e ...0.2.1....0.1.0....2.0.2....0.1.0....0.1.2....1.0.1....3.3.3....3.2.1
%e ..1.1.1.1..2.0.3.2..0.3.3.1..3.1.0.2..0.0.3.3..0.0.0.2..3.2.2.0..3.0.0.3
%Y Cf. A270509.
%K nonn
%O 1,2
%A _R. H. Hardin_, Mar 18 2016