Numbers k such that 2k - 1 divides 2^k + 1.

Terms

a(0) =1a(1) =194997a(2) =1463649a(3) =1957025a(4) =4657005a(5) =6464145a(6) =17214725a(7) =70930629a(8) =76938345a(9) =319359365a(10) =336837501a(11) =429872625a(12) =486213525a(13) =1343289717a(14) =1831683645a(15) =2163016845a(16) =2430979425a(17) =2950546137a(18) =3463374005a(19) =5031564525a(20) =5608791441a(21) =8993704797a(22) =9596401485a(23) =12556945401a(24) =13492461125a(25) =14559291285a(26) =18429009725