Numbers n such that 2^n - 21 is prime.

Terms

a(0) =1a(1) =2a(2) =3a(3) =4a(4) =5a(5) =6a(6) =7a(7) =9a(8) =11a(9) =13a(10) =14a(11) =21a(12) =23a(13) =41a(14) =46a(15) =89a(16) =110a(17) =389a(18) =413a(19) =489a(20) =869a(21) =1589a(22) =1713a(23) =2831a(24) =10843a(25) =11257a(26) =16949a(27) =24513a(28) =39621a(29) =43349