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Number of complementary pairs of tournaments on n nodes.
1

%I #17 Aug 27 2019 09:33:39

%S 1,1,2,3,10,34,272,3528,97144,4870920,452016608,77054901728,

%T 24271105072736,14200712295904928,15510501136026729216,

%U 31765207922047709885696,122456389219489134370435456,891699423142395494501906828160,12302820585630191716774996205431296

%N Number of complementary pairs of tournaments on n nodes.

%H Andrew Howroyd, <a href="/A059735/b059735.txt">Table of n, a(n) for n = 1..50</a>

%H Nevena Francetić, Sarada Herke, Ian M. Wanless, <a href="https://arxiv.org/abs/1703.04764">Parity of Sets of Mutually Orthogonal Latin Squares</a>, arXiv:1703.04764 [math.CO], 2017. See Section 4.1.

%H V. A. Liskovets, <a href="http://www.cs.uwaterloo.ca/journals/JIS/VOL3/LISK/Derseq.html">Some easily derivable sequences</a>, J. Integer Sequences, 3 (2000), #00.2.2.

%F Average of A000568 and A002785.

%t A000568 = Cases[Import["https://oeis.org/A000568/b000568.txt", "Table"], {_, _}][[All, 2]];

%t A002785 = Cases[Import["https://oeis.org/A002785/b002785.txt", "Table"], {_, _}][[All, 2]];

%t a[n_] := (A000568[[n + 1]] + A002785[[n]])/2;

%t Array[a, 19] (* _Jean-François Alcover_, Aug 27 2019 *)

%Y Cf. A000568, A002785.

%K nonn,easy

%O 1,3

%A _N. J. A. Sloane_, Feb 09 2001

%E More terms from Pab Ter (pabrlos2(AT)yahoo.com), Nov 06 2005

%E Terms a(18) and beyond from _Andrew Howroyd_, Sep 17 2018