Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).
%I #4 Mar 01 2015 12:05:04
%S 16384,65536,256012,803246,2036844,4542671,9169016,17232696,30665992,
%T 52227111,85761364,136522338,211563872,320215410,474655320,690599060,
%U 988121664,1392636938,1936059024,2658175636,3608266324,4847003609
%N Number of length n+6 0..3 arrays with at most two downsteps in every n consecutive neighbor pairs
%C Row 6 of A255660
%H R. H. Hardin, <a href="/A255666/b255666.txt">Table of n, a(n) for n = 1..210</a>
%F Empirical: a(n) = (1/39916800)*n^11 + (1/302400)*n^10 + (143/725760)*n^9 + (137/20160)*n^8 + (686191/1209600)*n^7 + (68821/4800)*n^6 + (118924709/725760)*n^5 + (37326349/60480)*n^4 + (9666601859/907200)*n^3 - (165778309/8400)*n^2 + (24588142/3465)*n - 6396 for n>4
%e Some solutions for n=2
%e ..1....2....0....0....1....2....1....0....0....2....3....3....2....2....2....3
%e ..0....3....3....1....1....3....1....0....2....0....2....1....3....3....3....3
%e ..3....3....2....1....0....2....0....3....3....2....2....1....0....1....1....0
%e ..3....0....0....3....0....3....2....0....3....2....3....1....0....3....3....3
%e ..1....2....0....0....2....1....2....3....1....1....1....2....2....1....0....2
%e ..0....3....0....1....0....3....2....0....2....3....2....3....1....3....3....3
%e ..2....2....0....1....2....1....1....1....3....2....1....1....0....1....3....0
%e ..0....1....0....1....3....2....1....1....0....3....0....1....0....2....0....0
%Y Cf. A255660
%K nonn
%O 1,1
%A _R. H. Hardin_, Mar 01 2015