Odd numbers k such that k and phi(k) have the same number of divisors.

Terms

a(0) =1a(1) =3a(2) =15a(3) =255a(4) =65535a(5) =77805a(6) =161595a(7) =331695a(8) =575025a(9) =664335a(10) =765765a(11) =1601145a(12) =2250885a(13) =2380833a(14) =2690415a(15) =3271905a(16) =3828825a(17) =4107285a(18) =5181813a(19) =5778045a(20) =5871285a(21) =6007365a(22) =6613425a(23) =7448805a(24) =9258795a(25) =9787869a(26) =9935055a(27) =10503675a(28) =10554705a(29) =10724805