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Search: id:A133518
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| A133518 |
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Smallest k such that p(n)^3 + k is prime where p(n) is the n-th prime. |
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+0
8
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| 3, 2, 2, 4, 30, 6, 6, 4, 30, 2, 12, 18, 6, 24, 14, 14, 12, 10, 16, 2, 6, 4, 2, 14, 54, 6, 4, 18, 4, 2, 30, 26, 56, 10, 24, 12, 24, 10, 30, 2, 18, 6, 26, 24, 14, 28, 18, 10, 14, 10, 12, 24, 16, 6, 18, 2, 20, 6, 4, 12, 4, 6, 10, 2, 6, 14, 16, 4, 18, 10, 14, 14, 16, 24, 4, 12, 32, 16, 50, 12, 2
(list; graph; listen)
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OFFSET
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1,1
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EXAMPLE
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p(1)=2, 2^3 = 8. for even k, 2^r + k is even and thus not prime, so we only need consider odd k.
for k = 1: 8 + 1 = 9, which is 3^2 and not prime.
for k = 3: 8 + 3 = 11, which is prime, so 3 is the smallest number that can be added to 8 to make a new prime.
Hence a(1) = 3.
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CROSSREFS
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Cf. A030078, A054271, A091666, A133517, A133519, A133520, A133521, A133522, (A001223).
Sequence in context: A058743 A117970 A111241 this_sequence A120729 A092743 A139420
Adjacent sequences: A133515 A133516 A133517 this_sequence A133519 A133520 A133521
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KEYWORD
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easy,nonn
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AUTHOR
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Carl R. White (oeisfan(AT)phodd.net), Sep 14 2007
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