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%I #22 Oct 09 2019 20:57:21
%S 1,16,210,2236,19688,141812,838816,3998456,15324708,46358876,
%T 108478966,193892860,260303408,253897632,171158018,72002088,14772512
%N The profile of the backtrack tree for the sixteen queens problem.
%C The profile (p_0, p_1, ..., p_n) is the number of nodes at each level of the tree.
%C The backtrack tree as defined by Knuth has for the sixteen queens problem 1141190303 nodes.
%D D. E. Knuth, The Art of Computer Programming, Volume 4, Pre-fascicle 5B, Introduction to Backtracking, 7.2.2. Backtrack programming. 2018.
%H Wikipedia, <a href="https://en.wikipedia.org/wiki/Backtracking">Backtracking</a>
%H Wikipedia, <a href="https://en.wikipedia.org/wiki/Eight_queens_puzzle">Eight queens puzzle</a>
%F a(16) = A000170(16), the number of solutions.
%Y Cf. A000170, A319235.
%K nonn,fini,full
%O 0,2
%A _Peter Luschny_, Sep 15 2018
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