a(n) = least k such that the remainder when 21^k is divided by k is n.

Terms

a(0) =2a(1) =19a(2) =6a(3) =17a(4) =218a(5) =15a(6) =14a(7) =13a(8) =12a(9) =11a(10) =86a(11) =9249a(12) =214a(13) =133a(14) =69a(15) =4084085a(16) =106a(17) =39a(18) =422a(19) =581831a(20) =23a(21) =5053a(22) =38a(23) =9237a(24) =26a(25) =775a(26) =46a(27) =1253a(28) =206a(29) =51