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A013604
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a(n) = 3^n - prevprime(3^n), where prevprime(x) is the largest prime < x.
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7
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1, 2, 4, 2, 2, 2, 8, 8, 2, 20, 16, 58, 22, 8, 16, 98, 10, 10, 14, 8, 4, 2, 20, 28, 20, 20, 26, 22, 14, 26, 4, 34, 52, 56, 28, 10, 2, 10, 58, 38, 2, 122, 74, 34, 22, 22, 46, 44, 50, 46, 16, 124, 4, 10, 106, 10, 26, 220, 38, 160, 74, 8, 28, 104, 104, 38, 298, 94, 16
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OFFSET
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1,2
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LINKS
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FORMULA
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MAPLE
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seq(3^i-prevprime(3^i), i=1..100);
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MATHEMATICA
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PROG
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(PARI) a(n) = 3^n - precprime(3^n-1); \\ Michel Marcus, Sep 16 2016
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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James Kilfiger (mapdn(AT)csv.warwick.ac.uk)
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STATUS
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approved
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