209468698473domain: NAppears in sequencesa(0) = 1, a(1) = 1; for n>0, a(2*n) = 3*a(2n-1), a(2*n+1) = 3*a(2*n) - 2*a(n-1).at n=25A102877a(n) = (A102877(n+1) - A102877(n))/2.at n=25A111017