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

%I A243464 #6 Jun 05 2014 18:46:32
%S A243464 0,0,3,110,657,2172,5375,11178,20685,35192,56187,85350,124553,175860,
%T A243464 241527,324002,425925,550128,699635,877662,1087617,1333100,1617903,
%U A243464 1946010,2321597,2749032,3232875,3777878,4388985,5071332,5830247,6671250,7600053,8622560
%N A243464 Number of ways 2 domicules can be placed on an n X n square.
%H A243464 Alois P. Heinz, <a href="/A243464/b243464.txt">Table of n, a(n) for n = 0..1000</a>
%F A243464 G.f.: x^2*(43*x^3-137*x^2-95*x-3)/(x-1)^5.
%F A243464 a(n) = -43+63*n-4*n^2-24*n^3+8*n^4 for n>0, a(0) = 0.
%e A243464 a(2) = 3:
%e A243464 +---+  +---+  +---+
%e A243464 |o-o|  |o o|  |o o|
%e A243464 |   |  || ||  | X |
%e A243464 |o-o|  |o o|  |o o|
%e A243464 +---+  +---+  +---+.
%p A243464 a:= n-> `if`(n=0, 0, (((8*n-24)*n-4)*n+63)*n-43):
%p A243464 seq(a(n), n=0..50);
%Y A243464 Column k=2 of A243424.
%K A243464 nonn,easy
%O A243464 0,3
%A A243464 _Alois P. Heinz_, Jun 05 2014