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A119650
Numbers k such that (2^67 - 1) * 10^k + (2^257 - 1) is prime.
0
42, 62, 146, 210, 936, 1490, 7932, 25220, 25352, 37610, 39282, 44792
OFFSET
1,1
COMMENTS
Some of the larger entries may only correspond to probable primes.
REFERENCES
Jason Earls, "Mersenne's Mistake," Mathematical Bliss, Pleroma Publications, 2009, pages 157-169. ASIN: B002ACVZ6O. [From Jason Earls, Nov 25 2009]
LINKS
Jason Earls, Mersenne's Mistake, Bewildering Stories.
PROG
(PARI) is(n)=ispseudoprime((2^67-1)*10^n+(2^257-1)) \\ Charles R Greathouse IV, Jun 13 2017
(Python)
from sympy import isprime
def afind(limit, startk=0):
c1, c2, pow10 = 2**67-1, 2**257-1, 10**startk
for k in range(startk, limit+1):
if isprime(c1*pow10 + c2): print(k, end=", ")
pow10 *= 10
afind(1500) # Michael S. Branicky, Sep 12 2021
CROSSREFS
Cf. A000043.
Sequence in context: A053323 A363730 A248441 * A193343 A118074 A350641
KEYWORD
more,nonn
AUTHOR
Jason Earls, Jul 28 2006, Jul 06 2008
EXTENSIONS
a(7) from Michael S. Branicky, Sep 12 2021
a(8)-a(9) from Michael S. Branicky, Apr 05 2023
a(10)-a(12) from Michael S. Branicky, Oct 17 2024
STATUS
approved