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A264129 Number of (n+1) X (4+1) arrays of permutations of 0..n*5+4 with each element having index change +-(.,.) 0,0 0,2 or 1,2.

%I A264129 #11 Jan 04 2019 14:44:19
%S A264129 80,1040,13600,178000,2330000,30500000,399250000,5226250000,
%T A264129 68412500000,895531250000,11722656250000,153451562500000,
%U A264129 2008707031250000,26294316406250000,344197070312500000,4505598144531250000
%N A264129 Number of (n+1) X (4+1) arrays of permutations of 0..n*5+4 with each element having index change +-(.,.) 0,0 0,2 or 1,2.
%H A264129 R. H. Hardin, <a href="/A264129/b264129.txt">Table of n, a(n) for n = 1..210</a>
%F A264129 Empirical: a(n) = 15*a(n-1) - 25*a(n-2).
%F A264129 Empirical g.f.: 80*x*(1 - 2*x) / (1 - 15*x + 25*x^2). - _Colin Barker_, Jan 04 2019
%e A264129 Some solutions for n=4:
%e A264129 ..0..8..4..3..2....0..3..9..1..4....0..1..4..3..2....0..8..2..3..4
%e A264129 ..5.13..7..1..9....5..6.14..8..2....5..6..9..8..7...12.13.14..1..9
%e A264129 .10.11.14..6.12...17.13.12.11..7...12.11.10.13.14...10.18..5..6..7
%e A264129 .15.16.19.18.17...15.23.10.18.19...22.18.17.16.19...22.16.24.11.19
%e A264129 .20.21.24.23.22...20.21.22.16.24...20.23.15.21.24...20.21.15.23.17
%Y A264129 Column 4 of A264131.
%K A264129 nonn
%O A264129 1,1
%A A264129 _R. H. Hardin_, Nov 03 2015