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A319236 The profile of the backtrack tree for the sixteen queens problem. 1


%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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Last modified March 28 14:24 EDT 2020. Contains 333089 sequences. (Running on oeis4.)