125414domain: NAppears in sequencesa(n) = [ C(2n,n)/2^(n+2) ].at n=22A024505Eigensequence of A047999, Sierpinski's gasket.at n=22A166966a(0) = a(1) = 1; a(n+2) = Sum_{k=0..n} (binomial(n,k) mod 2) * a(k).at n=46A331520a(n) = Sum_{k=0..floor(n/3)} binomial(n-1-2*k,n-3*k) * binomial(2*k,k).at n=21A360309