Sigma applied to A096841 produces these repdigits: a[n]=A000203[A096841(n)].

Terms

a(0) =1a(1) =3a(2) =4a(3) =7a(4) =6a(5) =8a(6) =44a(7) =222a(8) =444a(9) =888a(10) =444a(11) =888a(12) =888a(13) =2222a(14) =6666a(15) =8888a(16) =8888a(17) =222222a(18) =88888a(19) =222222a(20) =444444a(21) =444444a(22) =888888a(23) =444444a(24) =444444a(25) =666666a(26) =888888a(27) =888888a(28) =888888a(29) =888888