Prime numbers n such that 2^n-1 is a prime that cannot be written in the form a^2+7*b^2.
A216519
Prime numbers n such that 2^n-1 is a prime that cannot be written in the form a^2+7*b^2.
Terms
- a(0) =2a(1) =5a(2) =17a(3) =89a(4) =107a(5) =521a(6) =4253a(7) =9689a(8) =9941a(9) =11213a(10) =19937a(11) =21701a(12) =86243a(13) =756839a(14) =859433a(15) =1398269a(16) =2976221a(17) =3021377a(18) =6972593a(19) =25964951a(20) =32582657a(21) =37156667a(22) =43112609
External references
- oeis: A216519