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A255110 Number of length n+3 0..2 arrays with at most one downstep in every n consecutive neighbor pairs. 1

%I

%S 81,216,441,789,1302,2032,3042,4407,6215,8568,11583,15393,20148,26016,

%T 33184,41859,52269,64664,79317,96525,116610,139920,166830,197743,

%U 233091,273336,318971,370521,428544,493632,566412,647547,737737,837720,948273

%N Number of length n+3 0..2 arrays with at most one downstep in every n consecutive neighbor pairs.

%C Row 3 of A255107.

%H R. H. Hardin, <a href="/A255110/b255110.txt">Table of n, a(n) for n = 1..210</a>

%F Empirical: a(n) = (1/120)*n^5 + (1/4)*n^4 + (59/24)*n^3 + (93/4)*n^2 + (1321/30)*n + 11.

%F Empirical g.f.: x*(81 - 270*x + 360*x^2 - 237*x^3 + 78*x^4 - 11*x^5) / (1 - x)^6. - _Colin Barker_, Jan 24 2018

%e Some solutions for n=4:

%e 1 0 2 0 2 0 2 0 2 0 2 0 1 0 0 0

%e 0 2 1 1 0 0 2 2 0 0 0 2 1 0 1 0

%e 0 0 1 1 0 0 2 1 0 0 0 1 2 0 0 0

%e 0 0 1 1 1 0 2 2 1 0 1 1 0 0 0 1

%e 1 1 1 2 1 0 0 2 1 0 1 2 2 1 0 2

%e 1 2 0 0 2 1 0 2 1 0 0 2 2 2 0 2

%e 1 1 2 1 2 2 2 1 2 0 2 1 2 2 0 0

%Y Cf. A255107.

%K nonn

%O 1,1

%A _R. H. Hardin_, Feb 14 2015

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Last modified October 25 19:28 EDT 2020. Contains 338012 sequences. (Running on oeis4.)