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A242929
Primes p such that 2^p - p^2 is prime.
1
5, 7, 17, 19, 53, 83, 227, 461, 2221, 3547, 9029, 119087
OFFSET
1,1
COMMENTS
a(12) > 23053. - Robert Israel, Jun 10 2014
FORMULA
a(n) = prime(A117587(n)). - Daniel Suteu, Jun 25 2022
EXAMPLE
5 is in this sequence because 5 and 2^5 - 5^2 = 7 are both prime.
MAPLE
select(p -> isprime(p) and isprime(2^p - p^2), {2} union {seq(2*i+1, i=1..2000)}); # Robert Israel, Jun 10 2014
MATHEMATICA
Select[Prime[Range[300]], PrimeQ[2^# - #^2] &] (* Alonso del Arte, May 27 2014 *)
PROG
(Magma) [p: p in PrimeUpTo(2200) | IsPrime(2^p - p^2)];
(PARI) isok(p) = isprime(p) && ispseudoprime(2^p - p^2); \\ Daniel Suteu, Jun 25 2022
CROSSREFS
Subsequence of A072180.
Sequence in context: A196670 A075304 A168245 * A128490 A023519 A023517
KEYWORD
nonn,more
AUTHOR
EXTENSIONS
a(9) from Alonso del Arte, May 27 2014
a(10) from Alois P. Heinz, May 28 2014
a(11) from Robert Israel, Jun 10 2014
a(12) added by Daniel Suteu, Jun 25 2022
STATUS
approved