Permanents of (0,1) matrices :: classification

[Meeussen Wouter (bkarnd)]

seqfanners,

since the Permanent of a (square) (0,1)-matrix is conserved under
permutation of rows and\or columns,
one might wonder how many 'base forms' of such matrices exist:

           baseform= sortrows( sortcolumns(sortrows( matrix) ) )

throwing this definition over all (0,1) matrices from 1x1 opto 4x4
I find:          2,  7,  45,  660

(! EIS : no match!  Huh? 
is this sorting technique too irrelevant? I checked that it 'fixpoints' !)

Superseeker produced only matches thru substitutions & deletions..


Wouter.


Mma:
Table[Length at Split[Sort[baseform/@(Partition[#,n]&/@(
IntegerDigits[Range[0,-1+2^n^2],2,n^2]))]],{n,4}]









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