Number of palindromes of length <= n.

Terms

a(0) =10a(1) =19a(2) =109a(3) =199a(4) =1099a(5) =1999a(6) =10999a(7) =19999a(8) =109999a(9) =199999a(10) =1099999a(11) =1999999a(12) =10999999a(13) =19999999a(14) =109999999a(15) =199999999a(16) =1099999999a(17) =1999999999a(18) =10999999999a(19) =19999999999a(20) =109999999999a(21) =199999999999