A263711 - OEIS

%I #8 Jan 02 2019 23:12:27

%S 1,2,6,14,31,34,39,46,64,104,161,249,385,561,845,1254,1871,2833,4228,

%T 6359,9545,14273,21453,32133,48184,72323,108363,162592,243817,365545,

%U 548369,822181,1233053,1849282,2772959,4158841,6236608,9352579,14026153

%N Number of length n arrays of permutations of 0..n-1 with each element moved by -2 to 2 places and every four consecutive elements having its maximum within 4 of its minimum.

%H R. H. Hardin, <a href="/A263711/b263711.txt">Table of n, a(n) for n = 1..210</a>

%F Empirical: a(n) = a(n-1) + a(n-3) - a(n-4) + 2*a(n-5) - a(n-6) + a(n-7) for n>18.

%F Empirical g.f.: x*(1 + x + 4*x^2 + 7*x^3 + 16*x^4 - 3*x^5 - 6*x^6 - 21*x^7 - 9*x^8 - 19*x^9 - x^10 - 5*x^11 + 9*x^12 - 2*x^13 + 6*x^14 - 9*x^15 - 4*x^17) / (1 - x - x^3 + x^4 - 2*x^5 + x^6 - x^7). - _Colin Barker_, Jan 02 2019

%e Some solutions for n=7:

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

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

%e ..4....2....2....3....4....3....3....3....1....3....4....2....1....2....4....2

%e ..2....3....3....4....3....4....4....2....3....4....2....4....4....3....3....4

%e ..3....5....4....2....2....2....2....4....4....2....5....3....3....4....2....5

%e ..6....4....5....6....6....6....5....5....5....5....3....5....5....6....5....3

%e ..5....6....6....5....5....5....6....6....6....6....6....6....6....5....6....6

%Y Column 2 of A263714.

%K nonn

%O 1,2

%A _R. H. Hardin_, Oct 24 2015