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A219669
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Primes neighboring a 5-smooth number.
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1
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2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 47, 53, 59, 61, 71, 73, 79, 89, 97, 101, 107, 109, 127, 149, 151, 163, 179, 181, 191, 193, 199, 239, 241, 251, 257, 269, 271, 359, 383, 401, 431, 433, 449, 479, 487, 499, 541, 577, 599, 601, 641, 647, 719, 751
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OFFSET
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1,1
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COMMENTS
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This is to A219528 as 3-smooth numbers A003586 are to 5-smooth numbers A051037. The first primes NOT within one of a 5-smooth number are 83, 103, 113, 131, 137, 139, 157, ....
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LINKS
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Table of n, a(n) for n=1..57.
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FORMULA
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Primes INTERSECTION {2^i 3^j 5^k +/-1 for i,j,k >= 0}.
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EXAMPLE
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a(1) = 2 = 2^0 3^0 5^0 + 1 = 2^0 3^1 5^0 - 1.
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MATHEMATICA
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mx = 2^10; t5 = Select[Sort[Flatten[Table[2^i * 3^j * 5^k, {i, 0, Log[2, mx]}, {j, 0, Log[3, mx]}, {k, 0, Log[5, mx]}]]], # <= mx &]; Union[Select[t5 + 1, PrimeQ], Select[t5 - 1, PrimeQ]] (* T. D. Noe, Nov 25 2012 *)
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CROSSREFS
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Cf. A000040, A051037, A219528.
Sequence in context: A052042 A245576 A086472 * A109611 A181325 A078133
Adjacent sequences: A219666 A219667 A219668 * A219670 A219671 A219672
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KEYWORD
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nonn,easy
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AUTHOR
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Jonathan Vos Post, Nov 24 2012
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EXTENSIONS
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Corrected by T. D. Noe, Nov 25 2012
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STATUS
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approved
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