%I A083276
%S A083276 1,20,400,5362,72078,822518,9417681,96400068,988187354,9183421888
%N A083276 Number of distinct chess positions after n plies including differences 
               due to availability and possibility of castling and en passant captures.
%C A083276 This differs from A057745 at 6 ply and above because where an en passant 
               capture would be illegal, the position is essentially the same as 
               where an en passant capture is not available. It is two less than 
               A057745 at 6 ply because the positions after 1. f4 e6/e5 2. Kf2 Qf6 
               3. f5 g5 are considered to be the same as after 1. f4 g5 2. Kf2 e6/
               e5 3. f5 Qf6.
%C A083276 Definition: position = position with castling and en passant information, 
               diagram = position without castling and en passant information.
%H A083276 Tim Krabbe's chess blog, <a href="http://www.xs4all.nl/~timkr/chess2/
               diary.htm">Item 283</a> [Mentions schachzahl1b_e.html]
%H A083276 Author?, <a href="http://www.chessbox.de/Compu/schachzahl1b_e.html">Title?</
               a> [a serious approximation to the number of possible chess positions 
               is 2.28*10^46.]
%H A083276 <a href="Sindx_Ch.html#chess">Index entries for sequences related to 
               number of chess games</a>
%Y A083276 Cf. A019319, A048987, A057745, A089957.
%Y A083276 Sequence in context: A090051 A089957 A019319 this_sequence A057745 A009964 
               A007577
%Y A083276 Adjacent sequences: A083273 A083274 A083275 this_sequence A083277 A083278 
               A083279
%K A083276 hard,nonn,nice
%O A083276 0,2
%A A083276 Richard Bean (rwb(AT)eskimo.com), Jun 02 2003
%E A083276 a(9) from Paul Byrne (ibid(AT)carolina.rr.com), Jan 26 2004