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A270607 Number of 2X2X2 triangular 0..n arrays with some element plus some adjacent element totalling n+1 or n-1 exactly once. 1

%I

%S 6,0,36,36,96,120,204,252,360,432,564,660,816,936,1116,1260,1464,1632,

%T 1860,2052,2304,2520,2796,3036,3336,3600,3924,4212,4560,4872,5244,

%U 5580,5976,6336,6756,7140,7584,7992,8460,8892,9384,9840,10356,10836,11376

%N Number of 2X2X2 triangular 0..n arrays with some element plus some adjacent element totalling n+1 or n-1 exactly once.

%C Row 2 of A270606.

%H R. H. Hardin, <a href="/A270607/b270607.txt">Table of n, a(n) for n = 1..210</a>

%F Empirical: a(n) = 2*a(n-1) -2*a(n-3) +a(n-4) for n>5

%F Empirical for n mod 2 = 0: a(n) = 6*n^2 - 18*n + 12 for n>1

%F Empirical for n mod 2 = 1: a(n) = 6*n^2 - 18*n + 36 for n>1

%e Some solutions for n=4

%e ...4....2....4....4....3....2....1....0....1....3....1....4....0....1....0....2

%e ..0.3..4.3..1.0..2.3..2.4..3.4..4.3..4.3..0.3..4.0..3.0..3.2..2.1..4.0..1.2..0.1

%Y Cf. A270606.

%K nonn

%O 1,1

%A _R. H. Hardin_, Mar 20 2016

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Last modified August 14 13:00 EDT 2020. Contains 336480 sequences. (Running on oeis4.)