%N In chess, the number of "at home" dual-free proof games in n plies.
%C Among all the proof game problems counted in A090051, this is the number of problems where all the surviving pieces are apparently on their start squares.
%H A. Buchanan, <a href="http://anselan.com/CHE.html">"At Home" proof games</a>
%H F. Labelle, <a href="http://www.cs.berkeley.edu/~flab/chess/statistics-positions.html#at-home">Statistics on "at home" diagrams</a>
%H F. Labelle, <a href="http://www.pairlist.net/pipermail/retros/2005-February/001041.html">Mailing list posting about the computation up to ply 14</a>
%Y Cf. A090051.
%A _François Labelle_, Feb 11 2005
%E a(15)-a(16) from _François Labelle_, Apr 01 2015