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A099439
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Numbers k such that A000295(k) = 2^k-k-1 is prime.
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5
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4, 10, 14, 16, 26, 50, 56, 70, 116, 2072, 6250, 13670, 14216, 14626, 396128
(list;
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OFFSET
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1,1
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COMMENTS
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The next term is > 400000.
Equals A063791 + 1. - Herman Jamke (hermanjamke(AT)fastmail.fm), Jan 03 2008
Some of the results were computed using the PrimeFormGW (PFGW) primality-testing program. - Hugo Pfoertner, Nov 14 2019
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LINKS
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Table of n, a(n) for n=1..15.
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EXAMPLE
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a(1) = 4 because 2^4 - 4 - 1 = 11 is prime.
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CROSSREFS
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Cf. A000295 (2^n-n-1), A099440 (primes in A000295), A099441 (2^n-n-1 is a semiprime), A099442 (semiprimes in A000295).
Sequence in context: A310361 A310362 A310363 * A310364 A310365 A310366
Adjacent sequences: A099436 A099437 A099438 * A099440 A099441 A099442
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KEYWORD
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nonn,more,hard
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AUTHOR
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Hugo Pfoertner, Oct 18 2004
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EXTENSIONS
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a(15) (a PRP) from Karsten Bonath, Jun 07 2018
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STATUS
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approved
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