Numbers k such that k^3 divides 20^(k^2) + 1.

Terms

a(0) =1a(1) =3a(2) =7a(3) =21a(4) =381a(5) =903a(6) =921a(7) =2667a(8) =5789a(9) =6447a(10) =17367a(11) =18543a(12) =73703a(13) =114681a(14) =116967a(15) =208443a(16) =221109a(17) =277221a(18) =746781a(19) =797349a(20) =818769a(21) =855141a(22) =871347a(23) =1459101a(24) =2205609a(25) =2354961a(26) =5090367a(27) =5331669a(28) =5692701a(29) =6099429