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A176680
Primes p == 2 (mod 3) of the form 2^n-3.
3
5, 29, 509, 536870909, 13164036458569648337239753460458804039861886925068638906788872189, 3369993333393829974333376885877453834204643052817571560137951281149, 13803492693581127574869511724554050904902217944340773110325048447598589
OFFSET
1,1
COMMENTS
Also primes of the form 2^(2k+1)-3, since 2^n-3 == 2 (mod 3) iff n is odd. - Robert Israel, Feb 17 2016
LINKS
MAPLE
map(t -> 2^t-3, select(t -> isprime(2^t-3), [seq(t, t=1..2000, 2)])); # Robert Israel, Feb 17 2016
MATHEMATICA
Flatten[Table[If[IntegerQ[Rationalize[N[ (1 + 2^n)/ 3]]] && PrimeQ[2^n - 3], 2^n - 3, {}], {n, 2, 100000}]]
PROG
(Magma) [2^n-3: n in [1..300] | IsPrime(2^n-3) and (2^n-3) mod 3 eq 2] - Jaroslav Krizek, Feb 17 2016
CROSSREFS
Cf. A050414.
Sequence in context: A202758 A197962 A259534 * A352948 A352951 A069142
KEYWORD
nonn
AUTHOR
Roger L. Bagula, Apr 23 2010
EXTENSIONS
Definition corrected by Jaroslav Krizek, Feb 17 2016
a(5)-a(7) from Jaroslav Krizek, Feb 17 2016
STATUS
approved