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A370008
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a(n) is the greatest prime less than 3*prime(n).
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3
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5, 7, 13, 19, 31, 37, 47, 53, 67, 83, 89, 109, 113, 127, 139, 157, 173, 181, 199, 211, 211, 233, 241, 263, 283, 293, 307, 317, 317, 337, 379, 389, 409, 409, 443, 449, 467, 487, 499, 509, 523, 541, 571, 577, 587, 593, 631, 661, 677, 683, 691, 709, 719, 751
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OFFSET
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1,1
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LINKS
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EXAMPLE
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5 < 3*2 < 7 < 3*3 < 11 < 13 < 3*5, so (a(1), a(2), a(3)) = (5,7,13).
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MATHEMATICA
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Table[Prime[PrimePi[3*Prime[n]]], {n, 1, 200}]
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PROG
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(PARI) a(n) = precprime(3*prime(n)); \\ Michel Marcus, Feb 10 2024
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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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