a(n) is the sum of the digits of all positive integers k <= 2^n.

Terms

a(0) =1a(1) =3a(2) =10a(3) =36a(4) =73a(5) =177a(6) =460a(7) =1083a(8) =2395a(9) =5616a(10) =13645a(11) =28410a(12) =61237a(13) =139332a(14) =288640a(15) =617238a(16) =1349299a(17) =2868414a(18) =5996665a(19) =12814005a(20) =28009981a(21) =57356550a(22) =119204515a(23) =256361433a(24) =523470583a(25) =1084937169a(26) =2295828010a(27) =4741694379a(28) =9785380105a(29) =20385048345