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Number of self-converse relations on n points.
(Formerly M1868 N0740)
3

%I M1868 N0740 #23 Jan 29 2022 01:05:38

%S 1,2,8,44,436,7176,222368,12376880,1302871456,254079924896,

%T 94287450368768,65986000800656832,88430997899765949952,

%U 226039101814259861321856,1112311767839787173832758784

%N Number of self-converse relations on n points.

%D F. Harary and E. M. Palmer, Graphical Enumeration, Academic Press, NY, 1973, p. 155, Table 6.6.1.

%D N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).

%D N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

%H Sean A. Irvine, <a href="/A002500/b002500.txt">Table of n, a(n) for n = 0..50</a>

%H F. Harary and E. M. Palmer, <a href="http://dx.doi.org/10.1112/S0025579300003910">Enumeration of self-converse digraphs</a>, Mathematika, 13 (1966), 151-157.

%F Equals A029849*2 - A000595. Cf. A002499.

%K nonn,nice,easy

%O 0,2

%A _N. J. A. Sloane_

%E In the Encyclopedia of Integer Sequences the n=6 term is given incorrectly as 484256.

%E Corrected and extended with formula by _Christian G. Bower_, Jun 15 1998