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Number of labeled lattices with a fixed bottom.
4

%I #8 Jan 02 2020 08:23:50

%S 1,1,2,9,76,1065,22566,674611,27019896,1393871121,89805306250,

%T 7051089328371,661327038073428,72882388902988561,9308502142507505406,

%U 1361778362223282167235,225917426273413368357616,42135305039539420956486369

%N Number of labeled lattices with a fixed bottom.

%t A055512 = Cases[Import["https://oeis.org/A055512/b055512.txt", "Table"], {_, _}][[All, 2]];

%t a[n_] := A055512[[n + 1]]/n;

%t a /@ Range[18] (* _Jean-François Alcover_, Jan 02 2020 *)

%Y a(n) = A055512(n)/n = A058165(n)*(n-1). Main diagonal of A058160.

%K nonn,hard

%O 1,3

%A _Christian G. Bower_, Nov 15 2000

%E a(18) from _Jean-François Alcover_, Jan 02 2020