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%I #8 Jan 07 2019 06:24:07
%S 8,32,132,556,2324,9724,40692,170268,712468,2981244,12474676,52198876,
%T 218420308,913955132,3824342132,16002528156,66960773524,280189801724,
%U 1172422611892,4905870136668,20528060064468,85897351187644
%N Number of (n+1) X (3+1) arrays of permutations of 0..n*4+3 with each element having directed index change 0,0 0,1 1,0 or -1,-2.
%H R. H. Hardin, <a href="/A264280/b264280.txt">Table of n, a(n) for n = 1..210</a>
%F Empirical: a(n) = 3*a(n-1) +4*a(n-2) +4*a(n-3).
%F Empirical g.f.: 4*x*(2 + 2*x + x^2) / (1 - 3*x - 4*x^2 - 4*x^3). - _Colin Barker_, Jan 07 2019
%e Some solutions for n=4:
%e ..0..1..2..3....0..1..2..3....6..0..1..3....0..7..2..3....0..1..2..3
%e ..4.11..5..6....4.11..6..7....4.11..2..7....4..1..5..6....4..5..6..7
%e ..8..9.10..7...14..5..9.10...14..5..9.10....8.15..9.11....8..9.10.11
%e .12.19.14.15....8.19.13.15....8.19.13.15...18.13.10.14...12.19.13.14
%e .16.13.17.18...12.16.17.18...12.16.17.18...12.16.17.19...16.17.18.15
%Y Column 3 of A264285.
%K nonn
%O 1,1
%A _R. H. Hardin_, Nov 10 2015
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