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%I #24 Dec 26 2020 06:36:47
%S 20,20,31,32,46,48,52,55,61,63
%N Maximal number of possible moves at the n-th ply of a chess game.
%C In view of the 75-moves rule any chess game is finite.
%C The largest value appearing in the sequence is thought to be 218. - _François Labelle_, Dec 01 2016
%H A. Dickins, <a href="http://www.talkchess.com/forum/viewtopic.php?topic_view=threads&p=410026&t=39332">Record number of legal moves in a legal position</a>, 1968
%H <a href="/index/Ch#chess">OEIS index to sequences related to chess</a>.
%e In the initial position of the chess game, each player has 20 possible moves (16 pawn moves and 4 knight moves), and the first (half-)move made by White does not affect the 20 possibilities Black will have thereafter.
%e At its second move, i.e., ply 3 of the game, White may have as much as 31 possible moves, if White started with e2-e4 as first move, and Black offered a pawn with d7-d5 or f7-f5.
%Y Cf. A278831: minimal number of possible moves at the n-th ply.
%Y Cf. A278832: maximal material difference at the end of the n-th ply.
%Y Cf. A083276.
%K nonn,hard,more,fini
%O 1,1
%A _M. F. Hasler_, Nov 29 2016
%E a(3)-a(4) corrected and a(5)-a(10) from _François Labelle_, Nov 29 2016
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