Index of the first superabundant number k having abundance >= n.

Terms

a(0) =1a(1) =4a(2) =11a(3) =23a(4) =43a(5) =82a(6) =149a(7) =278a(8) =471a(9) =853a(10) =1378a(11) =2594a(12) =4474a(13) =7999a(14) =15747a(15) =27458a(16) =48615a(17) =84320a(18) =166806a(19) =297146a(20) =544525a(21) =973799