Numbers k that divide the sum of digits of 21^k.

Terms

a(0) =1a(1) =3a(2) =6a(3) =9a(4) =12a(5) =18a(6) =57a(7) =84a(8) =87a(9) =102a(10) =117a(11) =216a(12) =234a(13) =288a(14) =360a(15) =468a(16) =477a(17) =681a(18) =741a(19) =798a(20) =987a(21) =1029a(22) =1161a(23) =1245a(24) =1251a(25) =1266a(26) =1449a(27) =1458a(28) =1500a(29) =1677