OFFSET
1,1
COMMENTS
These counts have not been reduced to take account of the symmetries of the board.
REFERENCES
E. R. Berlekamp, J. H. Conway and R. K. Guy, Winning Ways, Academic Press, NY, 2 vols., 1982; see Chapter 25.
D. E. Knuth, The Art of Computer Programming, Vol. 4A, Section 7.1.4.
EXAMPLE
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.
CROSSREFS
KEYWORD
nonn,nice
AUTHOR
Don Knuth, Feb 03 2008
EXTENSIONS
a(11) from Don Knuth, Mar 26 2008
a(12)-a(15) from Tomas Rokicki, Oct 31 2010
STATUS
approved