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Number of subgroups L of Z^n with the property that for every a in Z^n there exists precisely one b in L with d(a,b) <= 1. Here d denotes Euclidean distance.
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%I #9 Aug 19 2015 05:51:03

%S 1,1,2,8,72,384,3840,80640,645120,10321920,309657600,3715891200,

%T 102187008000,3310859059200,51011754393600,1428329123020800,

%U 68559797904998400,1942527607308288000

%N Number of subgroups L of Z^n with the property that for every a in Z^n there exists precisely one b in L with d(a,b) <= 1. Here d denotes Euclidean distance.

%F a(n) = 2^n*n!*sum(1/|Aut(G)|), where the sum is over all isomorphism classes of Abelian groups of order 2*n+1.

%K easy,nonn

%O 0,3

%A _Paul Boddington_, Jan 26 2004