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 A264218 Number of (1+1) X (n+1) arrays of permutations of 0..n*2+1 with each element having directed index change 0,0 0,1 1,0 -1,0 or 0,-2. 1

%I #10 Jan 06 2019 07:56:48

%S 4,17,56,172,561,1826,5880,18993,61424,198472,641297,2072482,6697372,

%T 21642593,69939048,226011412,730364961,2360204994,7627103920,

%U 24647309729,79648825312,257388562256,831762066401,2687874415810,8685980265204

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

%H R. H. Hardin, <a href="/A264218/b264218.txt">Table of n, a(n) for n = 1..210</a>

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

%F Empirical g.f.: x*(4 + 9*x + 14*x^2 + 2*x^3 - 5*x^4 - 2*x^5) / (1 - 2*x - 2*x^2 - 6*x^3 - 2*x^4 + 2*x^5 + x^6). - _Colin Barker_, Jan 06 2019

%e Some solutions for n=4:

%e ..0..1..4..2..9....5..6..1..2..9....0..3..1..2..4....5..1..4..2..3

%e ..5..6..7..3..8....0..8..7..3..4....5..8..6..7..9....0..6..7..8..9

%Y Row 1 of A264217.

%K nonn

%O 1,1

%A _R. H. Hardin_, Nov 08 2015

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Last modified June 25 13:13 EDT 2024. Contains 373705 sequences. (Running on oeis4.)