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A341214
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a(n) is the smallest prime p such that p, p - 1, p - 2, ..., p - n + 1 have 2, 4, 6, ..., 2*n divisors respectively.
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3
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OFFSET
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1,1
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COMMENTS
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a(n) is the smallest prime p such that tau(p) = tau(p - 1)/2 = tau(p - 2)/3 = ... = tau(p - n + 1)/n = 2, where tau(k) = the number of divisors of k (A000005).
No such prime p exists for n > 5, so a(5) is the final term. - Jon E. Schoenfield, Feb 07 2021
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LINKS
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EXAMPLE
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a(4) = 1019 because 1016, 1017, 1018 and 1019 have 8, 6, 4, and 2 divisors respectively and there is no smaller prime having this property (see A340872).
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CROSSREFS
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Cf. A341213 (similar sequence for natural numbers).
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KEYWORD
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nonn,fini,full
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AUTHOR
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STATUS
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approved
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