%I A089957
%S A089957 1,20,400,1862,9825,53516,311642,2018993,12150635,69284509
%N A089957 Number of chess positions that can be obtained in exactly one way in 
               n plies.
%C A089957 Definition: position = position with castling and en passant information, 
               diagram = position without castling and en passant information.
%C A089957 The positions are taken from the sets that are counted in A083276.
%H A089957 F. Labelle, <a href="http://www.cs.berkeley.edu/~flab/chess/statistics-positions.html">
               Statistics on chess positions</a>
%H A089957 <a href="Sindx_Ch.html#chess">Index entries for sequences related to 
               number of chess games</a>
%Y A089957 Cf. A083276, A090044.
%Y A089957 Sequence in context: A158534 A075843 A090051 this_sequence A019319 A083276 
               A057745
%Y A089957 Adjacent sequences: A089954 A089955 A089956 this_sequence A089958 A089959 
               A089960
%K A089957 nonn,hard
%O A089957 0,2
%A A089957 Francois Labelle (flab(AT)cs.berkeley.edu), Jan 12 2004
%E A089957 a(9) from Francois Labelle (flab(AT)cs.berkeley.edu), Mar 09 2004