OFFSET
0,6
EXAMPLE
The a(12) = 21 square plane partitions with distinct row sums and distinct column sums:
[twelve]
.
[64][73][82][91][54][63][72][81][44][53][53][62][62][71][43][43][52][52][61]
[11][11][11][11][21][21][21][21][31][22][31][22][31][31][32][41][32][41][41]
.
[221]
[211]
[111]
MATHEMATICA
Table[Sum[Length[Select[Union[Reverse/@Sort/@Tuples[IntegerPartitions[#, {Length[ptn]}]&/@ptn]], UnsameQ@@Total/@#&&UnsameQ@@Total/@If[#=={}, {}, Transpose[#]]&&And@@OrderedQ/@Reverse/@If[#=={}, {}, Transpose[#]]&]], {ptn, IntegerPartitions[n]}], {n, 0, 20}]
CROSSREFS
KEYWORD
nonn
AUTHOR
Gus Wiseman, Feb 07 2019
STATUS
approved