Numbers k that divide 2^(k-2) + 1.

Terms

a(0) =1a(1) =3a(2) =49737a(3) =717027a(4) =9723611a(5) =21335267a(6) =32390921a(7) =38999627a(8) =43091897a(9) =86071337a(10) =101848553a(11) =102361457a(12) =228911411a(13) =302948067a(14) =370219467a(15) =393664027a(16) =455781089a(17) =483464027a(18) =1040406177a(19) =1272206987a(20) =2371678553a(21) =2571052241a(22) =2648052857a(23) =3054713937a(24) =3597613307a(25) =3782971499a(26) =3917903851a(27) =4005163577a(28) =5419912241