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A264622 Number of (n+1) X (1+1) arrays of permutations of 0..n*2+1 with each element having directed index change -2,0 -1,0 0,-1 or 1,1.

%I A264622 #8 Jan 08 2019 12:29:42
%S A264622 0,1,2,1,1,4,6,5,7,15,21,23,34,58,80,101,149,230,319,431,629,928,1299,
%T A264622 1810,2617,3784,5336,7536,10828,15521,21992,31236,44713,63862,90741,
%U A264622 129177,184524,263178,374521,533619,761403,1085401,1545839,2203162
%N A264622 Number of (n+1) X (1+1) arrays of permutations of 0..n*2+1 with each element having directed index change -2,0 -1,0 0,-1 or 1,1.
%H A264622 R. H. Hardin, <a href="/A264622/b264622.txt">Table of n, a(n) for n = 1..210</a>
%F A264622 Empirical: a(n) = a(n-3) + 2*a(n-4) + a(n-5).
%F A264622 Empirical g.f.: x^2*(1 + x)^2 / (1 - x^3 - 2*x^4 - x^5). - _Colin Barker_, Jan 08 2019
%e A264622 All solutions for n=4:
%e A264622 ..1..5
%e A264622 ..3..0
%e A264622 ..8..2
%e A264622 ..7..4
%e A264622 ..9..6
%Y A264622 Column 1 of A264628.
%K A264622 nonn
%O A264622 1,3
%A A264622 _R. H. Hardin_, Nov 19 2015