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%I #58 Mar 18 2024 07:26:21
%S 1,4,32,344,4460,66532,1118398,20984924,437500380,10105541204,
%T 257860425672,7241521734020,222770819826574,7466859257161488,
%U 271156951835070930,10609740515840572076,444982726973034212924,19911203110764903275188,946564783226311159219150
%N Number of ways to place n^2 nonattacking kings on a 2n X 2n cylindrical chessboard.
%H Rintaro Matsuo, <a href="/A137432/b137432.txt">Table of n, a(n) for n = 0..384</a> (terms 1..31 from Alex V. Breger)
%H Vaclav Kotesovec, <a href="https://oeis.org/wiki/User:Vaclav_Kotesovec">Non-attacking chess pieces</a>, 6ed, 2013, pp. 209-210.
%H Artem M. Karavaev, <a href="https://web.archive.org/web/20111226142906/https://zealint.ru/koroli-na-cilindricheskoj-doske-predlozhenie.html">Zealint blog</a> (in Russian)
%H Rintaro Matsuo, <a href="https://github.com/windows-server-2003/OEIS_calculation/tree/master/contents/A137432">Polynomial-time algorithm</a>
%H Rintaro Matsuo, <a href="/A137432/a137432.txt">a(1)..a(800)</a>
%F Conjecture: limit of a(n+1)/(n*a(n)) as n->infinity is e.
%F a(n) ~ c * n^n, where c = 2*exp(1)*(exp(1) - 1)^2 / (exp(1) - 2)^2 = 31.1116835720490503682643922791052352237386275089... - _Vaclav Kotesovec_, Jul 29 2023, updated Mar 18 2024
%Y Cf. A018807, A173033.
%K nonn,nice
%O 0,2
%A _Vaclav Kotesovec_, Aug 31 2011
%E a(11)-a(12) from _Vaclav Kotesovec_, Sep 08 2011
%E a(13)-a(27) from Alex V. Breger, Sep 10 2011
%E a(28)-a(31) from Alex V. Breger, Sep 12 2011
%E a(0)=1 prepended by _Andrew Howroyd_, Mar 26 2023
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