a(n) = 9*5^n+1.

Terms

a(0) =10a(1) =46a(2) =226a(3) =1126a(4) =5626a(5) =28126a(6) =140626a(7) =703126a(8) =3515626a(9) =17578126a(10) =87890626a(11) =439453126a(12) =2197265626a(13) =10986328126a(14) =54931640626a(15) =274658203126