a(n) = number of decimal digits of A007505(n).

Terms

a(0) =1a(1) =1a(2) =2a(3) =2a(4) =2a(5) =3a(6) =3a(7) =4a(8) =6a(9) =11a(10) =12a(11) =14a(12) =18a(13) =20a(14) =24a(15) =29a(16) =32a(17) =44a(18) =63a(19) =66a(20) =93a(21) =99a(22) =119a(23) =139a(24) =142a(25) =250a(26) =384a(27) =987a(28) =1267a(29) =1546