%I
%S 1,2,12,83,417,3928,127425,4782725,285886827,29305144137,
%T 5078448221965,1689709601427846,898792333612812818,
%U 812773906928265250254,1327574905899625395329686
%N Number of n X n Life configurations that are "still Life"s (unchanged in one step).
%C These counts have not been reduced to take into account 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 The 83 still lifes for n=4 have wellknown names, explained in the book by Berlekamp et al.: 9 are blocks, 12 are snakes, 4 are tubs, 16 are boats, 8 are ships, 8 are aircraft carriers, 4 are beehives, 8 are eaters, 4 are loaves, 2 are barges, 4 are longboats, 2 are long barges, 1 is the pond and the other one is empty.
%Y Cf. A134963, A136279, A136280.
%K nonn
%O 1,2
%A _Don Knuth_, Mar 26 2008
%E a(1) and a(7) corrected and a(11)(15) added by _Tomas Rokicki_, Oct 29 2010
