43515domain: NAppears in sequences30 'Reverse and Add' steps are needed to reach a palindrome.at n=21A065319Somos's sequence {a(5,n)} defined in comment in A018896: a(0)=a(1)= ... = a(11) = 1; for n>=12, a(n) = (a(n-1)*a(n-11) + a(n-6)^2)/a(n-12).at n=30A271835