A032420 -id:A032420 - cp's OEIS frontend

3, 5, 7, 31, 37, 41, 61, 103, 137, 2053, 125887, 968467

Offset: 1

Muniru A Asiru, Dec 25 2018

Equivalently, primes p such that 141*2^p+1 is prime.

Subsequence of A032420.

Filtered([1..400],p->IsPrime(p) and IsPrime(141*2^p+1));

select(p->isprime(p) and isprime(141*2^p+1),[$1..400]);

Select[Prime[Range[140]],PrimeQ[141*2^#+1]&] (* Harvey P. Dale, Sep 04 2023 *)

2, 14, 914, 12614, 335522, 1567874

Offset: 1

select(k->isprime(139*2^k+1),[$0..1000])[]; # Muniru A Asiru, Dec 18 2018

Select[Range[1000], PrimeQ[139*2^# + 1] & ] (* Robert Price, Dec 18 2018 *)

is(n)=ispseudoprime(139*2^n+1) \\ Charles R Greathouse IV, Jun 07 2017

One more term (from the Ballinger-Keller web page) from M. F. Hasler, Apr 18 2007

a(6) from the Ray Ballinger and Wilfrid Keller link by Robert Price, Dec 18 2018

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