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#91 by N. J. A. Sloane at Sun Jan 22 07:15:58 EST 2023
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#90 by N. J. A. Sloane at Sun Jan 22 07:15:53 EST 2023
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| NAME
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Primes of the form (10^k - 1)/9. Also called repunit primes or repdigit primes.
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| CROSSREFS
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A116692 is another version of repunit primes or repdigit primes. - N. J. A. Sloane, Jan 22 2023
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| EXTENSIONS
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Name expanded by N. J. A. Sloane, Jan 22 2023
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| STATUS
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approved
editing
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#89 by Charles R Greathouse IV at Thu Sep 08 08:44:32 EDT 2022
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| PROG
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(MAGMAMagma) [a: n in [0..300] | IsPrime(a) where a is (10^n - 1) div 9 ]; // Vincenzo Librandi, Nov 08 2014
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Discussion
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| Thu Sep 08
| 08:44
| OEIS Server: https://oeis.org/edit/global/2944
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#88 by Alois P. Heinz at Thu Jun 09 21:12:27 EDT 2022
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#87 by Michael S. Branicky at Thu Jun 09 20:28:53 EDT 2022
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#86 by Michael S. Branicky at Thu Jun 09 20:28:51 EDT 2022
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| PROG
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(Python)
from sympy import isprime
from itertools import count, islice
def agen(): # generator of terms
yield from (t for t in (int("1"*k) for k in count(1)) if isprime(t))
print(list(islice(agen(), 4))) # Michael S. Branicky, Jun 09 2022
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| STATUS
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approved
editing
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#85 by Michael De Vlieger at Fri Apr 01 20:20:00 EDT 2022
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#84 by Michael De Vlieger at Fri Apr 01 20:19:57 EDT 2022
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| LINKS
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Ernest G. Hibbs, <a href="https://www.proquest.com/openview/4012f0286b785cd732c78eb0fc6fce80">Component Interactions of the Prime Numbers</a>, Ph. D. Thesis, Capitol Technology Univ. (2022), see p. 33.
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| STATUS
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reviewed
editing
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#83 by Michel Marcus at Fri Apr 01 14:57:32 EDT 2022
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#82 by Michael De Vlieger at Fri Apr 01 14:34:17 EDT 2022
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