A222460 - OEIS

%I #7 Mar 15 2018 10:12:17

%S 343,556549,903055069,1465295106499,2377584520856755,

%T 3857863258420747009,6259760185235726701945,

%U 10157072698503130798653535,16480843155302567299412163919,26741778775464749134872807556861

%N Number of n X 4 0..7 arrays with no entry increasing mod 8 by 7 rightwards or downwards, starting with upper left zero.

%C Column 4 of A222462.

%H R. H. Hardin, <a href="/A222460/b222460.txt">Table of n, a(n) for n = 1..210</a>

%F Empirical: a(n) = 1689*a(n-1) - 108775*a(n-2) + 1672631*a(n-3).

%F Empirical g.f.: 7*x*(49 - 3254*x + 50519*x^2) / (1 - 1689*x + 108775*x^2 - 1672631*x^3). - _Colin Barker_, Mar 15 2018

%e Some solutions for n=3:

%e ..0..4..2..3....0..0..6..3....0..2..0..1....0..0..2..0....0..4..4..6

%e ..0..0..4..1....0..0..4..1....0..0..2..5....0..0..3..4....0..0..1..7

%e ..0..0..4..6....0..0..6..3....0..0..4..2....0..0..6..2....0..0..3..7

%Y Cf. A222462.

%K nonn

%O 1,1

%A _R. H. Hardin_, Feb 21 2013