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Search: id:A133520
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| A133520 |
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Smallest k such that p(n)^4 + k is prime where p(n) is the n-th prime. |
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+0
8
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| 1, 2, 6, 10, 12, 10, 16, 16, 6, 12, 18, 16, 12, 28, 6, 22, 6, 16, 6, 16, 6, 16, 30, 6, 16, 42, 22, 42, 28, 52, 22, 16, 28, 10, 28, 70, 30, 42, 78, 36, 12, 42, 6, 12, 40, 12, 12, 16, 16, 16, 18, 10, 6, 22, 60, 46, 76, 46, 18, 126, 12, 22, 22, 6, 16, 16, 22, 18, 120, 22, 12, 6, 6, 36
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OFFSET
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1,2
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EXAMPLE
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p(2)=3, 3^4 = 81; for odd k, and n > 1, p(n)^r + k is even and thus not prime, so we only need consider even k.
for k = 2: 81 + 2 = 83, which is prime, so 2 is the smallest number that can be added to 81 to make a new prime.
Hence a(2) = 2.
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CROSSREFS
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Cf. A030814, A054271, A091666, A133517, A133518, A133519, A133521, A133522, (A001223).
Sequence in context: A125241 A116043 A085258 this_sequence A099017 A139799 A139710
Adjacent sequences: A133517 A133518 A133519 this_sequence A133521 A133522 A133523
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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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