%I A056940
%S A056940 1,1,1,1,5,1,1,15,15,1,1,35,105,35,1,1,70,490,490,70,1,1,126,1764,
%T A056940 4116,1764,126,1,1,210,5292,24696,24696,5292,210,1,1,330,13860,116424,
%U A056940 232848,116424,13860,330,1,1,495,32670,457380,1646568,1646568,457380
%N A056940 Number of antichains (or order ideals) in the poset 4*m*n or plane partitions 
               with rows <= m, columns <= n and entries <= 4
%C A056940 Determinants of 4 X 4 subarrays of Pascal's triangle A007318 (a matrix 
               entry being set to 0 when not present). - Gerald McGarvey (Gerald.McGarvey(AT)comcast.net), 
               Feb 24 2005
%D A056940 Berman and Koehler, Cardinalities of finite distributive lattices, Mitteilungen 
               aus dem Mathematischen Seminar Giessen, 121 (1976), p. 103-124
%D A056940 P. A. MacMahon, Combinatory Analysis, sect 495, 1916.
%D A056940 R. P. Stanley, Theory and application of plane partitions. II. Studies 
               in Appl. Math. 50 (1971), p. 259-279. Thm. 18.1
%D A056940 Paul Barry, On Integer-Sequence-Based Constructions of Generalized Pascal 
               Triangles, Journal of Integer Sequences, Vol. 9 (2006), Article 06.2.4.
%H A056940 P. A. MacMahon, <a href="http://www.hti.umich.edu/cgi/t/text/text-idx?c=umhistmath;
               idno=ABU9009">Combinatory analysis</a>.
%H A056940 <a href="Sindx_Pos.html#posets">Index entries for sequences related to 
               posets</a>
%F A056940 Product[ C(n+m+k, m+k)/C(n+k, k), {k, 0, 3} ].
%Y A056940 Cf. A000372, A056932, A001263, A056939, A056941.
%Y A056940 Antidiagonals sum to A005362 (Hoggatt sequence)
%Y A056940 Sequence in context: A008957 A136267 A109960 this_sequence A157523 A141691 
               A157147
%Y A056940 Adjacent sequences: A056937 A056938 A056939 this_sequence A056941 A056942 
               A056943
%K A056940 nonn,easy,tabl
%O A056940 0,5
%A A056940 Mitch Harris (Harris.Mitchell(AT)mgh.harvard.edu)