usigma(n) = 2n + d(n), where d(n) is the number of divisors of n.

Terms

a(0) =150a(1) =294a(2) =726a(3) =1014a(4) =1428a(5) =1734a(6) =2166a(7) =3174a(8) =5046a(9) =5766a(10) =8214a(11) =10086a(12) =11094a(13) =13254a(14) =16854a(15) =20886a(16) =22326a(17) =26934a(18) =30246a(19) =31974a(20) =37446a(21) =41334a(22) =47526a(23) =56454a(24) =61206a(25) =63654a(26) =68694a(27) =71286a(28) =76614a(29) =96774