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A059749 Numbers k such that 5*2^k - 7 is prime. 1
1, 2, 4, 6, 10, 16, 30, 32, 52, 68, 78, 84, 118, 136, 154, 406, 488, 696, 752, 880, 2754, 3922, 3976, 4888, 5866 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

The next terms are > 50000. - Jinyuan Wang, Feb 03 2020

LINKS

Table of n, a(n) for n=1..25.

MATHEMATICA

Do[ If[ PrimeQ[ 5*2^n - 7 ], Print[n] ], {n, 3000} ]

Select[Range[6000], PrimeQ[(5*2^# - 7)] &] (* Vincenzo Librandi, Sep 30 2012 *)

PROG

(PARI) is(n)=ispseudoprime(5*2^n-7) \\ Charles R Greathouse IV, Jun 13 2017

(PFGW) ABC2 5*2^$a-7

a: from 1 to 10000 // Jinyuan Wang, Feb 03 2020

CROSSREFS

Cf. A059748 (5*2^k + 7 is prime).

Sequence in context: A018161 A288599 A067880 * A334213 A164142 A048833

Adjacent sequences:  A059746 A059747 A059748 * A059750 A059751 A059752

KEYWORD

nonn,more

AUTHOR

Robert G. Wilson v, Feb 10 2001

EXTENSIONS

a(22)-a(25) from Vincenzo Librandi, Sep 30 2012

STATUS

approved

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Last modified October 21 16:40 EDT 2021. Contains 348155 sequences. (Running on oeis4.)