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Numbers k such that 2^k - 2*k + 1 is prime.
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%I #33 Sep 08 2022 08:46:20

%S 0,3,5,6,8,11,12,13,18,25,31,35,114,152,186,228,245,308,360,371,575,

%T 685,721,732,1361,2394,3138,3446,5964,9482,22793,51233,112800,120491,

%U 199615,416641

%N Numbers k such that 2^k - 2*k + 1 is prime.

%C Terms through 1361 correspond to provable primes; terms beyond 1361 correspond to probable primes.

%C After 22793, there are no more terms through 40000. - _Jon E. Schoenfield_, Mar 27 2018

%C a(37) > 5*10^5. - _Robert Price_, Jun 01 2018

%p select(k->isprime(2^k-2*k+1),[$0..3000]); # _Muniru A Asiru_, Apr 03 2018

%t Select[Range[0, 1000], PrimeQ[2^# - 2*# + 1] &]

%o (Magma) [n: n in [0..1000] |IsPrime(2^n-2*n+1)]; // _Vincenzo Librandi_, Mar 27 2018

%o (PARI) isok(n) = isprime(2^n-2*n+1); \\ _Michel Marcus_, Mar 27 2018

%Y Cf. A100359, A100361, A301634.

%K nonn,more,hard

%O 1,2

%A _Vaclav Kotesovec_, Mar 26 2018

%E a(31) from _Jon E. Schoenfield_, Mar 27 2018

%E a(32)-a(34) from _Robert Price_, Apr 03 2018

%E a(35)-a(36) from _Robert Price_, Jun 01 2018