1,2

For n = 1 2^1 + 27 = 29

For n = 2 2^2 + 27 = 31

For n = 4 2^4 + 27 = 43

Delete[Union[Table[If[PrimeQ[2^n + 27], n, 0], {n, 1, 2000}]], 1]

A019434 (2^(2^n)+1) A057733 (2^n+3) A123250 (2^n+5)

A104071 (Primes of the form 2^n+27)

Sequence in context: A123886 A005242 A115392 this_sequence A007729 A144876 A072437

Adjacent sequences: A157004 A157005 A157006 this_sequence A157008 A157009 A157010

nonn

Edwin Dyke (ed.dyke(AT)btinternet.com), Feb 20 2009