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A096820
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Exponents n such that 2^n-21 is prime.
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9
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5, 6, 7, 9, 11, 13, 14, 21, 23, 41, 46, 89, 110, 389, 413, 489, 869, 1589, 1713, 2831, 10843, 11257, 16949, 24513, 39621, 43349, 62941, 96094, 139237, 145289
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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LINKS
| Search for 2^n-21, PRP Top Records
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EXAMPLE
| n=5: 32-21=11 is prime; n=7: 128-21=107 is prime.
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MATHEMATICA
| Select[Range[5, 20000], PrimeQ[2^#-21]&] (*From Vladimir Joseph Stephan Orlovsky, Feb 27 2011*)
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CROSSREFS
| Exponents for primes of 2^n-d form: A000043 (d=1), A050414 (d=3), A059608 (d=5), A059609 (d=7), A059610 (d=9), A096817 (d=11), A096818 (d=13), A059612 (d=15), A059611 (d=17), A096819 (d=19), A096820 (d=21).
Cf. A096502
Sequence in context: A132829 A180061 A196029 * A175154 A164317 A030388
Adjacent sequences: A096817 A096818 A096819 * A096821 A096822 A096823
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KEYWORD
| nonn,more,changed
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AUTHOR
| Labos E. (labos(AT)ana.sote.hu), Jul 13 2004
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EXTENSIONS
| a(23)-a(24) from Max Alekseyev, a(25) from Donovan Johnson, a(26)-a(28) from Henri Lifchitz, a(29)-a(30) from Lelio R Paula, added by Max Alekseyev (maxale(AT)gmail.com), Feb 10 2012
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