a(n) = (10^(2*n+1) - 1)/9 + 4*10^n.A332115a(n) = (10^(2*n+1) - 1)/9 + 4*10^n.Terms a(0) =5a(1) =151a(2) =11511a(3) =1115111a(4) =111151111a(5) =11111511111External referencesoeis: A332115