Self-composition of the sum of divisors function (A000203).

Terms

a(0) =1a(1) =6a(2) =26a(3) =101a(4) =366a(5) =1294a(6) =4400a(7) =14706a(8) =48362a(9) =157583a(10) =507714a(11) =1621211a(12) =5138804a(13) =16204008a(14) =50867068a(15) =159004142a(16) =494928072a(17) =1534638702a(18) =4743180908a(19) =14622202326a(20) =44978845086a(21) =138074363360a(22) =422979847404