%I A038720
%S A038720 2,5,18,84,480,3240,25200,221760,2177280,23587200,279417600,3592512000,
%T A038720 49816166400,741015475200,11769069312000,198766503936000,
%U A038720 3556874280960000,67224923910144000,1338096104497152000
%N A038720 Next-to-last diagonal of A038719.
%D A038720 R. B. Nelsen and H. Schmidt, Jr., Chains in power sets, Math. Mag., 64 
               (1991), 23-31.
%H A038720 <a href="Sindx_Pos.html#posets">Index entries for sequences related to 
               posets</a>
%F A038720 (n+3)*n!/2. Half A052572.
%Y A038720 Cf. A038721.
%Y A038720 Sequence in context: A137861 A111916 A118187 this_sequence A157312 A089412 
               A058798
%Y A038720 Adjacent sequences: A038717 A038718 A038719 this_sequence A038721 A038722 
               A038723
%K A038720 nonn,easy
%O A038720 1,1
%A A038720 N. J. A. Sloane (njas(AT)research.att.com), May 02 2000
%E A038720 Corrected and extended by Larry Reeves (larryr(AT)acm.org), May 09 2000.