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 A243464 Number of ways 2 domicules can be placed on an n X n square. 2

%I #6 Jun 05 2014 18:46:32

%S 0,0,3,110,657,2172,5375,11178,20685,35192,56187,85350,124553,175860,

%T 241527,324002,425925,550128,699635,877662,1087617,1333100,1617903,

%U 1946010,2321597,2749032,3232875,3777878,4388985,5071332,5830247,6671250,7600053,8622560

%N Number of ways 2 domicules can be placed on an n X n square.

%H Alois P. Heinz, <a href="/A243464/b243464.txt">Table of n, a(n) for n = 0..1000</a>

%F G.f.: x^2*(43*x^3-137*x^2-95*x-3)/(x-1)^5.

%F a(n) = -43+63*n-4*n^2-24*n^3+8*n^4 for n>0, a(0) = 0.

%e a(2) = 3:

%e +---+ +---+ +---+

%e |o-o| |o o| |o o|

%e | | || || | X |

%e |o-o| |o o| |o o|

%e +---+ +---+ +---+.

%p a:= n-> `if`(n=0, 0, (((8*n-24)*n-4)*n+63)*n-43):

%p seq(a(n), n=0..50);

%Y Column k=2 of A243424.

%K nonn,easy

%O 0,3

%A _Alois P. Heinz_, Jun 05 2014

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Last modified December 6 18:41 EST 2023. Contains 367614 sequences. (Running on oeis4.)