Composite numbers k such that sigma(k) / d(k) is prime.

Terms

a(0) =6a(1) =20a(2) =45a(3) =49a(4) =150a(5) =169a(6) =361a(7) =832a(8) =961a(9) =1445a(10) =1734a(11) =1849a(12) =5329a(13) =8405a(14) =9409a(15) =9477a(16) =10086a(17) =10609a(18) =14580a(19) =14641a(20) =16129a(21) =17405a(22) =20886a(23) =24649a(24) =25205a(25) =30246a(26) =39601a(27) =39605a(28) =47526a(29) =49729