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A245997 Number of length 2+2 0..n arrays with no pair in any consecutive three terms totalling exactly n 1

%I

%S 2,12,68,208,534,1116,2120,3648,5930,9100,13452,19152,26558,35868,

%T 47504,61696,78930,99468,123860,152400,185702,224092,268248,318528,

%U 375674,440076,512540,593488,683790,783900,894752,1016832,1151138,1298188

%N Number of length 2+2 0..n arrays with no pair in any consecutive three terms totalling exactly n

%C Row 2 of A245995

%H R. H. Hardin, <a href="/A245997/b245997.txt">Table of n, a(n) for n = 1..210</a>

%F Empirical: a(n) = 3*a(n-1) -a(n-2) -5*a(n-3) +5*a(n-4) +a(n-5) -3*a(n-6) +a(n-7).

%F Empirical: G.f.: -2*x*(1+3*x+17*x^2+13*x^3+14*x^4) / ( (1+x)^2*(x-1)^5 ). - _R. J. Mathar_, Aug 10 2014

%e Some solutions for n=10

%e ..5....2....2....2....8....9....2....4....6....8....8....5....3....0....1....6

%e ..0....2....7....7....7....4....9...10....7....6...10....0....6....4....2...10

%e ..1....1...10....2....5....3....6....4....2....6....7....7....0....4....6....9

%e ..8....1....5....7....0....3....9....5....6....3...10....7....0...10....2....3

%K nonn

%O 1,1

%A _R. H. Hardin_, Aug 09 2014

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Last modified December 11 21:28 EST 2019. Contains 329937 sequences. (Running on oeis4.)