OFFSET
1,2
COMMENTS
a(49) > 5*10^5. - Robert Price, Nov 06 2015
LINKS
Henri Lifchitz and Renaud Lifchitz, Search for 2^n+27, PRP Top Records.
EXAMPLE
For k = 1, 2^1 + 27 = 29.
For k = 2, 2^2 + 27 = 31.
For k = 4, 2^4 + 27 = 43.
MATHEMATICA
Delete[Union[Table[If[PrimeQ[2^n + 27], n, 0], {n, 1, 2000}]], 1]
Select[Range[5000], PrimeQ[2^#+27]&] (* Harvey P. Dale, Mar 24 2011 *)
PROG
(PARI) for(n=1, 1e3, if(isprime(2^n+3^3), print1(n", "))) \\ Altug Alkan, Oct 04 2015
(Magma) [n: n in [0..1000] | IsPrime(2^n+27)]; // Vincenzo Librandi, Oct 05 2015
CROSSREFS
Cf. A019434 (primes 2^k+1), A057732 (2^k+3), A059242 (2^k+5), A057195 (2^k+7), A057196 (2^k+9), A102633 (2^k+11), A102634 (2^k+13), A057197 (2^k+15), A057200 (2^k+17), A057221 (2^k+19), A057201 (2^k+21), A057203 (2^k+23), A157006 (2^k+25), this sequence (2^k+27), A156982 (2^k+29), A247952 (2^k+31), A247953 (2^k+33), A220077 (2^k+35).
KEYWORD
nonn
AUTHOR
Edwin Dyke (ed.dyke(AT)btinternet.com), Feb 20 2009
EXTENSIONS
More terms from Harvey P. Dale, Mar 24 2011
a(33)-a(42) from Robert Price, Oct 04 2015
a(43)-a(47) discovered by Henri Lifchitz and Lelio R Paula from Lifchitz link by Robert Price, Oct 04 2015
a(48) from Robert Price, Nov 06 2015
STATUS
approved