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A206581
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Odd primes p such that p+1 is a prime times a power of two.
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7
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5, 11, 13, 19, 23, 37, 43, 47, 61, 67, 73, 79, 103, 151, 157, 163, 191, 193, 211, 223, 271, 277, 283, 313, 331, 367, 383, 397, 421, 457, 463, 487, 523, 541, 547, 607, 613, 631, 661, 673, 691, 733, 751, 757, 787, 823, 877, 907, 991, 997, 1051, 1087, 1093
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OFFSET
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1,1
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COMMENTS
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Very similar to A192869; here p+1 = q*2^k, where q must be prime.
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LINKS
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T. D. Noe, Table of n, a(n) for n = 1..1000
Kevin Broughan and Zhou Qizhi, Flat primes and thin primes, Bulletin of the Australian Mathematical Society 82:2 (2010), pp. 282-292.
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FORMULA
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a(n) >> n log^2 n is implicit in Broughan & Qizhi, see A192869. - Charles R Greathouse IV, Sep 15 2015
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MATHEMATICA
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Select[Prime[Range[2, 1000]], PrimeQ[(#+1)/2^IntegerExponent[#+1, 2]] &]
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PROG
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(PARI) is(n)=isprime(n) && n>4 && isprime((n+1)>>valuation(n+1, 2)) \\ Charles R Greathouse IV, Sep 15 2015
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CROSSREFS
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Subsequence of A192869.
Sequence in context: A340466 A222219 A023225 * A292940 A098085 A104216
Adjacent sequences: A206578 A206579 A206580 * A206582 A206583 A206584
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KEYWORD
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nonn
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AUTHOR
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T. D. Noe, Mar 07 2012
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STATUS
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approved
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