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A264245 Number of (1+1) X (n+1) arrays of permutations of 0..n*2+1 with each element having directed index change 0,0 1,1 0,-1 -1,1 or 0,-2. 1

%I #10 Jan 06 2019 10:42:28

%S 2,8,21,57,164,460,1289,3629,10202,28672,80609,226609,637024,1790792,

%T 5034233,14152073,39783914,111839432,314399813,883831849,2484603092,

%U 6984645780,19635038321,55197463509,155169545554,436208230272

%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 1,1 0,-1 -1,1 or 0,-2.

%H R. H. Hardin, <a href="/A264245/b264245.txt">Table of n, a(n) for n = 1..210</a>

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

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

%e Some solutions for n=4:

%e ..1..5..2..7..4....0..1..6..3..4....1..2..6..7..4....2..5..6..4..8

%e ..6..0..8..9..3....5..7..8..2..9....5..0..8..9..3....7..0..1..9..3

%Y Row 1 of A264244.

%K nonn

%O 1,1

%A _R. H. Hardin_, Nov 09 2015

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Last modified June 19 00:17 EDT 2024. Contains 373492 sequences. (Running on oeis4.)