127425domain: NAppears in sequencesa(n) = Sum{a(k): k=0,1,2,...,n-4,n-2,n-1}; a(n-3) is not a summand; initial terms are 1,2,4.at n=19A049870Number of n X n Life configurations that are "still Life"s (unchanged in one step).at n=6A136278