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%I M5164 #9 Mar 30 2012 16:45:08
%S 1,0,0,0,0,24,570,27900,1827630,152031600,15453884376,1884221030160,
%T 271711899360000,45788222207669040,8922353083744943700,
%U 1991728039234615305624,505133808398958249480060
%N Number of labeled 2-regular oriented graphs with n nodes.
%D R. W. Robinson, personal communication.
%D R. W. Robinson, Numerical implementation of graph counting algorithms, AGRC Grant, Math. Dept., Univ. Newcastle, Australia, 1982.
%D N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
%H R. W. Robinson, <a href="/A007109/b007109.txt">Table of n, a(n) for n = 0..48</a>
%K nonn
%O 0,6
%A _N. J. A. Sloane_.