a(1) = 1; a(n) = 2*a(n-1) + (number of digits in a(n-1)).

Terms

a(0) =1a(1) =3a(2) =7a(3) =15a(4) =32a(5) =66a(6) =134a(7) =271a(8) =545a(9) =1093a(10) =2190a(11) =4384a(12) =8772a(13) =17548a(14) =35101a(15) =70207a(16) =140419a(17) =280844a(18) =561694a(19) =1123394a(20) =2246795a(21) =4493597a(22) =8987201a(23) =17974409a(24) =35948826a(25) =71897660a(26) =143795328a(27) =287590665a(28) =575181339a(29) =1150362687