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A083722
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Product of primes greater than the greatest prime factor of n but not greater than n.
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6
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1, 1, 1, 3, 1, 5, 1, 105, 35, 7, 1, 385, 1, 143, 1001, 15015, 1, 85085, 1, 323323, 46189, 4199, 1, 37182145, 7436429, 7429, 37182145, 1062347, 1, 215656441, 1, 100280245065, 86822723, 392863, 955049953, 33426748355, 1, 765049, 247110827, 247357937827, 1, 1448810778701, 1
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OFFSET
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1,4
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COMMENTS
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a(n) = 1 iff n is prime or n is 1.
Apart from 1-terms, the other duplicated terms are: a(24) = a(27), a(120) = a(125), a(140) = a(147), a(528) = a(539), etc, whose positions are listed by A293893 and A293894. - Antti Karttunen, Nov 01 2017
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LINKS
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FORMULA
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MATHEMATICA
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Array[Times @@ Select[Prime@ Range[#1, #1 + #2], Function[p, p <= #3]] & @@ {PrimePi@ NextPrime[FactorInteger[#][[-1, 1]]], PrimePi@ #, #} &, 43] (* Michael De Vlieger, Nov 01 2017 *)
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PROG
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(PARI) a(n) = {if (n==1, return (1)); my(gpf = vecmax(factor(n)[, 1])); my(pp = 1); forprime(p=gpf+1, n, pp *= p; ); pp; } \\ Michel Marcus, Jun 26 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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EXTENSIONS
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STATUS
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approved
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