%I A123544
%S A123544 0,0,1,6,87,1980,66270,3050460,184716630,14231775600,1359481407480,
%T A123544 157694893448400,21835679256606600,3557942554594428000,
%U A123544 673941365091485290800,146851484638349504613600
%N A123544 Number of connected labeled 2-regular relations of order n.
%D A123544 R. W. Robinson, Numerical implementation of graph counting algorithms, 
               AGRC Grant, Math. Dept., Univ. Newcastle, Australia, 1982.
%H A123544 R. W. Robinson, <a href="b123544.txt">Table of n, a(n) for n = 0..48</
               a>
%Y A123544 Connected version of A001499.
%Y A123544 Sequence in context: A013527 A047786 A113666 this_sequence A138216 A122770 
               A127183
%Y A123544 Adjacent sequences: A123541 A123542 A123543 this_sequence A123545 A123546 
               A123547
%K A123544 nonn
%O A123544 0,4
%A A123544 N. J. A. Sloane (njas(AT)research.att.com), Nov 13 2006