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A194263
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Numbers that occur more than once in A193873, in order of appearance.
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2
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1729, 13981, 88537, 51319, 137149, 548497, 285541, 3372529, 18326641, 1152271, 1809641, 3828001, 4814857, 4797703, 79230049, 4413223, 4209661, 19703611, 3882139, 50357677, 70611161, 26536591, 175493677, 85409941, 12932989, 84350561, 192754871, 59756863
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OFFSET
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1,1
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COMMENTS
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Note that a(1) = 1729 is known as the Hardy-Ramanujan number (see A001235).
Apparently these numbers occur only twice in A193873.
Many of these numbers occur more than twice. For example, 812405017 occurs 3 times, a(67), a(134), and a(268). Robert Price, Mar 17 2020
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LINKS
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FORMULA
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It appears that a(n) = A193873(2*n+1).
This conjecture only holds for n<62: a(62)=A193873(124)=A193873(2n)=620378449
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EXAMPLE
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1729 is in the sequence because the Hardy-Ramanujan number is also the smallest product of three distinct primes of the form 3*k+1 and also of the form 6*k+1, so 1729 occurs more than once in A193873.
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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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