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A065380
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Primes of the form p + 2^k, p prime and k >= 0.
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4
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3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97, 101, 103, 107, 109, 113, 131, 137, 139, 151, 157, 163, 167, 173, 179, 181, 191, 193, 197, 199, 211, 223, 227, 229, 233, 239, 241, 257, 263, 269, 271, 277, 281, 283, 293
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OFFSET
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1,1
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LINKS
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FORMULA
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EXAMPLE
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a(3) = 11 = 3 + 2^3 = 7 + 2^2.
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MATHEMATICA
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With[{upto=300}, Select[Union[Select[Flatten[Outer[Plus, Prime[Range[ PrimePi[upto]]], 2^Range[0, Floor[Log[2, upto]]]]], PrimeQ]], #<=upto&]] (* Harvey P. Dale, Feb 28 2012 *)
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PROG
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(Haskell)
a065380 n = a065380_list !! (n-1)
a065380_list = filter f a000040_list where
f p = any ((== 1) . a010051 . (p -)) $ takeWhile (<= p) a000079_list
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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