Table of n, a(n) for n=1..9.
a(3)=1 because there is only one distinct still life with three cells: a diagonal line of length three.
Cf. A019473, A166476, A175000, A175001
Sequence in context: A291377 A005297 A014551 * A088014 A193662 A279508
Adjacent sequences: A174999 A175000 A175001 * A175003 A175004 A175005
Christian Schroeder, Apr 03 2010