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 A002500 Number of self-converse relations on n points. (Formerly M1868 N0740) 3
 1, 2, 8, 44, 436, 7176, 222368, 12376880, 1302871456, 254079924896, 94287450368768, 65986000800656832, 88430997899765949952, 226039101814259861321856, 1112311767839787173832758784 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 REFERENCES F. Harary and E. M. Palmer, Graphical Enumeration, Academic Press, NY, 1973, p. 155, Table 6.6.1. N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence). N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence). LINKS Sean A. Irvine, Table of n, a(n) for n = 0..50 F. Harary and E. M. Palmer, Enumeration of self-converse digraphs, Mathematika, 13 (1966), 151-157. FORMULA Equals A029849*2 - A000595. Cf. A002499. CROSSREFS Sequence in context: A126101 A308478 A157994 * A002833 A139015 A197996 Adjacent sequences:  A002497 A002498 A002499 * A002501 A002502 A002503 KEYWORD nonn,nice,easy AUTHOR EXTENSIONS In the Encyclopedia of Integer Sequences the n=6 term is given incorrectly as 484256. Corrected and extended with formula by Christian G. Bower, Jun 15 1998 STATUS approved

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Last modified January 20 09:40 EST 2021. Contains 340302 sequences. (Running on oeis4.)