%N Number of configurations in Conway's game of "Life" that fit into an n X n square and vanish in one step.
%C These counts have not been reduced to take account of the symmetries of the board.
%D E. R. Berlekamp, J. H. Conway and R. K. Guy, Winning Ways, Academic Press, NY, 2 vols., 1982; see Chapter 25.
%D D. E. Knuth, The Art of Computer Programming, Vol. 4A, Section 7.1.4.
%e For example, a(2)=11 because the 2 X 2 configurations remain nonempty if and only if they have more than two live cells; 1 + 4 + 6 = 11.
%Y Cf. A136278, A136279, A136280.
%A _Don Knuth_, Feb 03 2008
%E a(11) from _Don Knuth_, Mar 26 2008
%E a(12)-a(15) from _Tomas Rokicki_, Oct 31 2010