Refactorable numbers: number of divisors of k divides k. Also known as tau numbers.

Terms

a(0) =1a(1) =2a(2) =8a(3) =9a(4) =12a(5) =18a(6) =24a(7) =36a(8) =40a(9) =56a(10) =60a(11) =72a(12) =80a(13) =84a(14) =88a(15) =96a(16) =104a(17) =108a(18) =128a(19) =132a(20) =136a(21) =152a(22) =156a(23) =180a(24) =184a(25) =204a(26) =225a(27) =228a(28) =232a(29) =240