A255621 - OEIS

%I #4 Feb 28 2015 11:37:13

%S 3834,9186,23298,60390,156563,405687,1047141,2656032,6682971,16925280,

%T 43249522,110788455,283416570,724728391,1851244551,4719321474,

%U 12020625692,30651759318,78266507064,199890070327,510335125536

%N Number of length n+7 0..2 arrays with at most two downsteps in every 7 consecutive neighbor pairs

%C Column 7 of A255622

%H R. H. Hardin, <a href="/A255621/b255621.txt">Table of n, a(n) for n = 1..210</a>

%F Empirical: a(n) = 3*a(n-1) -3*a(n-2) +a(n-3) +12*a(n-4) -18*a(n-5) +7*a(n-6) +153*a(n-7) -237*a(n-8) +95*a(n-9) -885*a(n-11) +1087*a(n-12) -123*a(n-13) -6870*a(n-14) +8984*a(n-15) -1401*a(n-16) -1260*a(n-17) +11772*a(n-18) -16266*a(n-19) +6696*a(n-20) +69471*a(n-21) -114183*a(n-22) +47448*a(n-23) -100*a(n-24) -17955*a(n-25) +5628*a(n-26) -700*a(n-27) -2565*a(n-28) +804*a(n-29) -100*a(n-30)

%e Some solutions for n=4

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

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

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

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

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

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

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

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

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

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

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

%Y Cf. A255622

%K nonn

%O 1,1

%A _R. H. Hardin_, Feb 28 2015