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Number of city-block distance 1, pressure limit 2 movements in an nX6 array with each element moving exactly one horizontally or vertically and no element acquiring more than two neighbors
1

%I #4 Sep 24 2012 09:03:16

%S 16,70225,103754596,174892912804,287247245656900,473216230511351044,

%T 778956312256094880625,1282337355733724881761856,

%U 2110951958198074542626828769,3475005538598697157658237172049

%N Number of city-block distance 1, pressure limit 2 movements in an nX6 array with each element moving exactly one horizontally or vertically and no element acquiring more than two neighbors

%C Column 6 of A217028

%H R. H. Hardin, <a href="/A217026/b217026.txt">Table of n, a(n) for n = 1..210</a>

%e Some solutions for n=2 (movement: 0=n 1=e 2=s 3=w)

%e ..2..3..2..3..1..3....1..2..2..3..3..3....2..2..1..3..3..2....2..3..2..2..2..3

%e ..0..1..1..1..1..0....0..0..3..3..0..3....0..3..0..1..1..3....0..0..0..1..0..0

%K nonn

%O 1,1

%A _R. H. Hardin_ Sep 24 2012