a(n) = 6*(10^(2*n+1)-1)/9 + 3*10^n.A332169a(n) = 6*(10^(2*n+1)-1)/9 + 3*10^n.Terms a(0) =9a(1) =696a(2) =66966a(3) =6669666a(4) =666696666a(5) =66666966666External referencesoeis: A332169