%I A005321 M1986
%S A005321 1,1,2,10,122,3346,196082,23869210,5939193962,2992674197026,
%T A005321 3037348468846562,6189980791404487210,25285903982959247885402
%N A005321 Upper triangular n X n (0,1)-matrices with no empty rows or columns.
%D A005321 N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, 
               Academic Press, 1995 (includes this sequence).
%D A005321 T. L. Greenough, Ph.D. Thesis, Dartmouth, circa 1975 [ from Tom Trotter 
               ].
%D A005321 Andresen, E.; Kjeldsen, K.; On certain subgraphs of a complete transitively 
               directed graph. Discrete Math. 14 (1976), no. 2, 103-119.
%H A005321 <a href="Sindx_Mat.html#binmat">Index entries for sequences related to 
               binary matrices</a>
%F A005321 Sum_{k=0..n} C(n, k)b(k), where b(0)=1, b(k+1) = (2^(k+1)-1)*b(k)+(-1)^(k+1) 
               [ A005327 ].
%F A005321 G.f.: Sum(x^n*Product((2^i-1)/(1+(2^i-1)*x),i = 1 .. n),n = 0 .. infinity). 
               - Vladeta Jovovic (vladeta(AT)eunet.rs), Mar 10 2008
%Y A005321 Sequence in context: A060690 A005617 A013038 this_sequence A092645 A144835 
               A119191
%Y A005321 Adjacent sequences: A005318 A005319 A005320 this_sequence A005322 A005323 
               A005324
%K A005321 nonn,easy,nice,more
%O A005321 0,3
%A A005321 N. J. A. Sloane (njas(AT)research.att.com).