A114736 Number of planar partitions of n where parts strictly decrease along each row and column.
1, 1, 1, 3, 4, 6, 10, 15, 22, 33, 49, 70, 102, 146, 205, 290, 405, 561, 779, 1071, 1463, 1999, 2714, 3667, 4946, 6641, 8880, 11848, 15753, 20870, 27586, 36354, 47766, 62621, 81878, 106785, 138975, 180449, 233778, 302270, 390027, 502256, 645603, 828330, 1060851
Offset: 0
Keywords
Examples
For n = 5, we have the 6 partitions [5], [4,1], [4|1], [3,2], [3|2] and [3,1|1]. From _Gus Wiseman_, Nov 15 2018: (Start) The a(6) = 10 plane partitions: 6 5 1 4 2 3 2 1 . 5 4 1 4 3 2 3 1 1 1 2 1 2 . 3 2 1 (End)
References
- B. Gordon, Multirowed partitions with strict decrease along columns (Notes on plane partitions IV.), Symposia Amer. Math. Soc. 19 (1971) 91-100.
Links
- Alois P. Heinz, Table of n, a(n) for n = 0..85
Crossrefs
Programs
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Mathematica
prs2mat[prs_]:=Table[Count[prs,{i,j}],{i,Union[First/@prs]},{j,Union[Last/@prs]}]; multsubs[set_,k_]:=If[k==0,{{}},Join@@Table[Prepend[#,set[[i]]]&/@multsubs[Drop[set,i-1],k-1],{i,Length[set]}]]; Table[Length[Select[multsubs[Tuples[Range[n],2],n],And[Union[First/@#]==Range[Max@@First/@#],Union[Last/@#]==Range[Max@@Last/@#],And@@(OrderedQ[#,Greater]&/@prs2mat[#]),And@@(OrderedQ[#,Greater]&/@Transpose[prs2mat[#]])]&]],{n,5}] (* Gus Wiseman, Nov 15 2018 *)
Extensions
Clarified definition, added 30 terms and reference. - Dennis K Moore, Jan 12 2011
a(40)-a(44) from Alois P. Heinz, Sep 26 2018
Comments