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A278246
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a(n) = least number with the same prime signature as n*(n+3)/2.
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4
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2, 2, 4, 6, 12, 8, 6, 12, 24, 6, 6, 60, 24, 6, 24, 24, 30, 24, 6, 30, 180, 12, 6, 144, 60, 6, 48, 30, 48, 60, 6, 240, 120, 6, 30, 120, 60, 6, 60, 60, 30, 120, 6, 30, 1080, 12, 12, 360, 60, 12, 48, 210, 60, 48, 30, 60, 420, 6, 6, 840, 96, 30, 120, 96, 210, 60, 30, 30, 360, 30, 6, 1800, 30, 30, 180, 30, 840, 96, 6, 120, 480, 30, 6, 420, 420, 6, 120, 420, 30, 120
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OFFSET
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1,1
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COMMENTS
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For n > 2, 6 <= a(n) <= n*(n+3)/2. The upper bound occurs for n = 1, 45, 165, 525, 672, 1152, and no others up to 10^9. (Probably this occurs only finitely many times.) - Charles R Greathouse IV, Nov 23 2016
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LINKS
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FORMULA
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PROG
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(PARI) A046523(n)=my(f=vecsort(factor(n)[, 2], , 4), p); prod(i=1, #f, (p=nextprime(p+1))^f[i])
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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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