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Number of nXnXn triangular 0..1 arrays with new values introduced in sequential zero-upwards order and exactly one inverted 2x2x2 triangle having values all equal.
2

%I #5 Apr 06 2016 09:55:07

%S 0,0,8,216,6048,203256,8627472,475098048,34505348760,3341298530016,

%T 434656549010376,76372500634028280,18198479103071529600,

%U 5898858710813046614376,2607147775322232410982384

%N Number of nXnXn triangular 0..1 arrays with new values introduced in sequential zero-upwards order and exactly one inverted 2x2x2 triangle having values all equal.

%C Column 1 of A271407.

%H R. H. Hardin, <a href="/A271400/b271400.txt">Table of n, a(n) for n = 1..20</a>

%e Some solutions for n=4

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

%e ....0.1......1.1......0.1......1.1......0.0......1.0......1.1......1.0

%e ...0.0.1....0.1.0....0.1.1....0.0.0....0.1.1....1.0.0....0.1.1....1.1.1

%e ..0.0.1.0..0.1.0.1..0.0.1.1..0.1.0.1..0.1.1.0..1.1.0.0..0.0.0.1..1.0.1.0

%Y Cf. A271407.

%K nonn

%O 1,3

%A _R. H. Hardin_, Apr 06 2016