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A262969 Numbers n such that 4^n + 27 is prime. 1
1, 2, 4, 5, 7, 8, 20, 22, 43, 55, 67, 77, 92, 97, 154, 160, 533, 748, 1432, 3143, 6427, 8257, 8270, 9623, 12269, 28822, 32683, 42638, 97427, 133340, 188395 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

The next terms are > 250000.

Contains exactly the halved even terms of A157007.

LINKS

Table of n, a(n) for n=1..31.

MATHEMATICA

Select[Range[0, 250000], PrimeQ[4^# + 27] &]

PROG

(MAGMA) [n: n in [0..700] | IsPrime(4^n+27)]; // Vincenzo Librandi, Oct 06 2015

(PARI) for(n=1, 1e3, if(isprime(4^n+3^3), print1(n", "))) \\ Altug Alkan, Oct 06 2015

CROSSREFS

Cf. A157007.

Cf. similar sequences of the type "Numbers n such that 4^n+k is prime" listed in A253772.

Sequence in context: A141493 A103118 A346140 * A158029 A217378 A140204

Adjacent sequences:  A262966 A262967 A262968 * A262970 A262971 A262972

KEYWORD

nonn,more

AUTHOR

Robert Price, Oct 05 2015

STATUS

approved

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Last modified October 16 20:36 EDT 2021. Contains 348047 sequences. (Running on oeis4.)