A030268 - OEIS

%I #16 Mar 17 2020 19:31:17

%S 1,1,1,3,9,35,153,791,4597,29988,215804,1697291,14457059,132392971,

%T 1295346365,13468653637,148142236784,1716782858995,20889118889021

%N Number of nonisomorphic connected partial lattices.

%C A partial lattice is a poset where every pair of points has a unique least upper (greatest lower) bound or has no upper (lower) bound.

%H N. J. A. Sloane, <a href="/transforms.txt">Transforms</a>

%F Inverse Euler transform of A006966(n-2) (lattices).

%t A006966 = Cases[Import["https://oeis.org/A006966/b006966.txt", "Table"], {_, _}][[All, 2]];

%t (* EulerInvTransform is defined in A022562 *)

%t Join[{1}, EulerInvTransform[Drop[A006966, 3]]] (* _Jean-François Alcover_, May 10 2019, updated Mar 17 2020 *)

%K nonn,hard

%O 0,4

%A _Christian G. Bower_, revised Dec 28 2000

%E a(17) (from A006966) from _Jean-François Alcover_, May 10 2019

%E a(18) (using A006966) from _Alois P. Heinz_, May 10 2019