a(1)=0 a(2)=1 a(n)=concatenate(a(n-1)a(n-2)...a(1))-a(n-1).

A069054

a(1)=0 a(2)=1 a(n)=concatenate(a(n-1)a(n-2)...a(1))-a(n-1).

Terms

    a(0) =0a(1) =1a(2) =9a(3) =901a(4) =901009a(5) =901009000901

External references