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A173903 Numbers n such that both (2^n+1)^2-2 and (2^n-1)^2-2 are prime. 0
2, 3, 12, 15, 18, 21, 27 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..7.

FORMULA

A091513 INTERSECT A091515. - R. J. Mathar, Jul 06 2010

MATHEMATICA

Select[Range[3000], PrimeQ[((2^# + 1)^2 - 2)]&&PrimeQ[((2^# - 1)^2 - 2)] &] (* Vincenzo Librandi, Aug 21 2014 *)

PROG

(MAGMA) [n: n in [1..400] | IsPrime((2^n-1)^2-2) and IsPrime((2^n+1)^2-2)]

CROSSREFS

Cf. A091513, A091515.

Sequence in context: A302844 A180630 A173079 * A154785 A090512 A076175

Adjacent sequences:  A173900 A173901 A173902 * A173904 A173905 A173906

KEYWORD

nonn,hard,more

AUTHOR

Vincenzo Librandi, Mar 08 2010

EXTENSIONS

Definition clarified by Jon E. Schoenfield, Jun 18 2010

STATUS

approved

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Last modified August 10 04:38 EDT 2020. Contains 336368 sequences. (Running on oeis4.)