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 A255663 Number of length n+3 0..3 arrays with at most two downsteps in every n consecutive neighbor pairs 1

%I

%S 256,1024,4048,14192,42653,112196,265430,577464,1174730,2262312,

%T 4162792,7370432,12625472,21014456,34103820,54115508,84155145,

%U 128505312,192998760,285488992,416438559,599648684,853157474,1200338032,1671232268

%N Number of length n+3 0..3 arrays with at most two downsteps in every n consecutive neighbor pairs

%C Row 3 of A255660

%H R. H. Hardin, <a href="/A255663/b255663.txt">Table of n, a(n) for n = 1..210</a>

%F Empirical: a(n) = (1/39916800)*n^11 + (1/403200)*n^10 + (1/9072)*n^9 + (109/40320)*n^8 + (63421/1209600)*n^7 + (39319/57600)*n^6 + (1888387/362880)*n^5 + (24707/2240)*n^4 + (4099087/453600)*n^3 + (33487/525)*n^2 + (950843/6930)*n + 28 for n>1

%e Some solutions for n=4

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

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

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

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

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

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

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

%Y Cf. A255660

%K nonn

%O 1,1

%A _R. H. Hardin_, Mar 01 2015

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Last modified January 28 23:12 EST 2022. Contains 350670 sequences. (Running on oeis4.)