|
| |
|
|
A136278
|
|
Number of n X n Life configurations that are "still Life"s (unchanged in one step).
|
|
2
| |
|
|
1, 2, 12, 83, 417, 3928, 127425, 4782725, 285886827, 29305144137, 5078448221965, 1689709601427846, 898792333612812818, 812773906928265250254, 1327574905899625395329686
(list; graph; refs; listen; history; internal format)
|
|
|
|
OFFSET
| 1,2
|
|
|
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
| The 83 still lifes for n=4 have well-known 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.
|
|
|
CROSSREFS
| Cf. A134963, A136279, A136280.
Sequence in context: A092850 A199420 A052864 * A130464 A006657 A105927
Adjacent sequences: A136275 A136276 A136277 * A136279 A136280 A136281
|
|
|
KEYWORD
| nonn
|
|
|
AUTHOR
| D. E. Knuth, Mar 26 2008
|
|
|
EXTENSIONS
| Corrected a(1) and a(7); added a(11) through a(15). Tomas Rokicki (rokicki(AT)gmail.com), Oct 29 2010
|
| |
|
|
