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URL: https://oeis.org/A138577

⇱ A138577 - OEIS

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A138577
Numbers n such that 2^(2*n-3)-3 is prime.
0
3, 4, 6, 16, 108, 112, 118, 274, 346, 1162, 1620
OFFSET
1,1
EXAMPLE
2^(2*3-3)-3=5, 2^(2*4-3)-3=29, 2^(2*6-3)-3=509,...
MATHEMATICA
q=3; For[i=q, i<=q, a={}; Do[x=2^(2*n-i)-i; If[PrimeQ[x], AppendTo[a, n]], {n, 10^2}]; Print["2^(2*n-", i, ")-", i, " ", a]; i=i+2]
Select[Range[400], PrimeQ[2^(2#-3)-3]&] (* Harvey P. Dale, Aug 10 2017 *)
PROG
(PARI) is(n)=isprime(2^(2*n-3)-3) \\ Charles R Greathouse IV, Jun 13 2017
CROSSREFS
Sequence in context: A092933 A122849 A068573 * A394081 A298149 A136242
KEYWORD
nonn,easy
AUTHOR
EXTENSIONS
More terms from Harvey P. Dale, Aug 10 2017
STATUS
approved