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A105467
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Number of irregular primes less than or equal to the 3^n-th prime.
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2
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0, 0, 5, 22, 91, 286, 863, 2577, 7717, 23160, 69939, 209485, 627826, 1881554, 5645226, 16936048
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OFFSET
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1,3
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COMMENTS
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Limit_{n->inf.} a(n)/3^n = 1-e^(-1/2).
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LINKS
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MATHEMATICA
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ip={ the list of irregular primes to 12 million }; Table[ Length[ Select[ip, # < Prime[3^n] &]], {n, 9}]
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CROSSREFS
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KEYWORD
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hard,nonn,more
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AUTHOR
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EXTENSIONS
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Terms corrected and a(10)-a(16) added by Amiram Eldar, Mar 05 2019
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STATUS
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approved
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