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A001772
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Numbers k such that 11*2^k - 1 is prime.
(Formerly M2145 N0854)
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3
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2, 26, 50, 54, 126, 134, 246, 354, 362, 950, 1310, 2498, 6926, 11826, 31734, 67850, 74726, 96150, 374114, 696438, 743322, 1044086, 1104606, 1261478
(list;
graph;
refs;
listen;
history;
text;
internal format)
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OFFSET
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1,1
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REFERENCES
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H. Riesel, "Prime numbers and computer methods for factorization", Progress in Mathematics, Vol. 57, Birkhäuser, Boston, 1985, Chap. 4, see pp. 381-384.
N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
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LINKS
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PROG
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(Python)
from sympy import isprime
def aupto(lim): return [k for k in range(1, lim+1) if isprime(11*2**k - 1)]
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CROSSREFS
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KEYWORD
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hard,nonn,nice,more
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AUTHOR
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EXTENSIONS
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More terms from Herman Jamke (hermanjamke(AT)fastmail.fm), Jan 02 2008
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STATUS
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approved
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