a(n) = concatenate(n, A010888(2*n), reverse(n)), where A010888 = digital root.

Terms

a(0) =121a(1) =242a(2) =363a(3) =484a(4) =515a(5) =636a(6) =757a(7) =878a(8) =999a(9) =10201a(10) =11411a(11) =12621a(12) =13831a(13) =14141a(14) =15351a(15) =16561a(16) =17771a(17) =18981a(18) =19291a(19) =20402a(20) =21612a(21) =22822a(22) =23132a(23) =24342a(24) =25552a(25) =26762a(26) =27972a(27) =28282a(28) =29492a(29) =30603