[seqfan] A001495

[David Newman]

This sequence is titled Number of Stochastic Matrices of Integers and it
begins

1,1,1,3,13,70.  I don't understand this.  It seems to me that for n=2 there
are two matrices of non-negative integers with row sums 1 and column sums
of 1, namely

((1,0),(0,1)) and ((0,1),(1,0)). So a(2) should be 2, not 1.   There is a
reference to an article called "Enumeration of Symmetric Matrices', but I
don't have access to this.  Can someone explain to me what is being counted
by this sequence?