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A301744 Numbers k such that 2^k - 2*k + 1 is prime. 0
0, 3, 5, 6, 8, 11, 12, 13, 18, 25, 31, 35, 114, 152, 186, 228, 245, 308, 360, 371, 575, 685, 721, 732, 1361, 2394, 3138, 3446, 5964, 9482, 22793, 51233, 112800, 120491, 199615, 416641 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

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

After 22793, there are no more terms through 40000. - Jon E. Schoenfield, Mar 27 2018

a(37) > 5*10^5. - Robert Price, Jun 01 2018

LINKS

Table of n, a(n) for n=1..36.

MAPLE

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

MATHEMATICA

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

PROG

(MAGMA) [n: n in [0..1000] |IsPrime(2^n-2*n+1)]; // Vincenzo Librandi, Mar 27 2018

(PARI) isok(n) = isprime(2^n-2*n+1); \\ Michel Marcus, Mar 27 2018

CROSSREFS

Cf. A100359, A100361, A301634.

Sequence in context: A268896 A014254 A131422 * A087720 A309544 A154111

Adjacent sequences:  A301741 A301742 A301743 * A301745 A301746 A301747

KEYWORD

nonn,more,hard

AUTHOR

Vaclav Kotesovec, Mar 26 2018

EXTENSIONS

a(31) from Jon E. Schoenfield, Mar 27 2018

a(32)-a(34) from Robert Price, Apr 03 2018

a(35)-a(36) from Robert Price, Jun 01 2018

STATUS

approved

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Last modified September 29 07:08 EDT 2020. Contains 337425 sequences. (Running on oeis4.)