OFFSET
0,4
COMMENTS
Number of ways to fill a (not necessarily square) matrix with the parts of an integer partition of n so that the rows and columns are weakly decreasing and with no repeated rows or columns.
EXAMPLE
The a(7) = 13 plane partitions:
[7] [4 3] [5 2] [6 1] [4 2 1]
.
[6] [5] [3 2] [4 1] [4] [2 2] [3 1]
[1] [2] [1 1] [1 1] [3] [2 1] [2 1]
.
[4]
[2]
[1]
MATHEMATICA
Table[Sum[Length[Select[Union[Tuples[IntegerPartitions[#, {k}]&/@ptn]], And[UnsameQ@@#, UnsameQ@@Transpose[#], And@@(OrderedQ[#, GreaterEqual]&/@Transpose[#])]&]], {ptn, IntegerPartitions[n]}, {k, Min[ptn]}], {n, 20}]
CROSSREFS
KEYWORD
nonn
AUTHOR
Gus Wiseman, Jan 15 2019
STATUS
approved