%I #4 Mar 30 2012 16:50:32
%S 1,1,1,5,19,205,1795,36317,636331,23679901,805351531,56294206205,
%T 3735873535339,502757743028605,65725984337422795,17309316971673776957,
%U 4485620580863732681131
%N Leading diagonal of A123260.
%D R. W. Robinson, Numerical implementation of graph counting algorithms, AGRC Grant, Math. Dept., Univ. Newcastle, Australia, 1977.
%H R. W. Robinson, <a href="/A123281/b123281.txt">Table of n, a(n) for n = 1..30</a>
%K nonn
%O 1,4
%A _N. J. A. Sloane_, Nov 12 2006