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A172411
Numbers n such that 2^n+9 and 2^n+27 are prime.
0
OFFSET
1,2
COMMENTS
No further terms between 10 and 5000. - R. J. Mathar, Feb 07 2010
No further terms to 100000. Expected number of remaining terms: (zeta(2) - 1 - 1/4 - ... - 1/100000^2)/log^2 2 ~= 0.00002. - Charles R Greathouse IV, Mar 25 2010
FORMULA
A057196 INTERSECT A157007 - R. J. Mathar, Feb 07 2010
EXAMPLE
a(1)=1 because 2^1+3^2=11 and 2^1+3^3=29 are prime.
MATHEMATICA
Select[Range[10], AllTrue[2^#+{9, 27}, PrimeQ]&] (* The program uses the AllTrue function from Mathematica version 10 *) (* Harvey P. Dale, May 28 2016 *)
PROG
(PARI) is(n)=isprime(2^n+9) && isprime(2^n+27) \\ Charles R Greathouse IV, Sep 06 2016
CROSSREFS
Sequence in context: A188948 A334295 A083460 * A264784 A306679 A125974
KEYWORD
nonn,less
AUTHOR
STATUS
approved