3506503681domain: NAppears in sequencesa(n) = Sum_{d|n} (2^(n-d)).at n=31A074854a(n)=2^(2^n)*sum(k=0,n,1/2^(2^k)).at n=5A085010A bisection of A006921.at n=31A260022Decimal representation of the middle column of the "Rule 126" elementary cellular automaton starting with a single ON (black) cell.at n=31A267367