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A137926
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a(n) = the largest divisor of n that is coprime to A000005(n). (A000005(n) = the number of positive divisors of n.).
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3
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1, 1, 3, 4, 5, 3, 7, 1, 1, 5, 11, 1, 13, 7, 15, 16, 17, 1, 19, 5, 21, 11, 23, 3, 25, 13, 27, 7, 29, 15, 31, 1, 33, 17, 35, 4, 37, 19, 39, 5, 41, 21, 43, 11, 5, 23, 47, 3, 49, 25, 51, 13, 53, 27, 55, 7, 57, 29, 59, 5, 61, 31, 7, 64, 65, 33, 67, 17, 69, 35, 71, 1, 73, 37, 25, 19, 77, 39, 79
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OFFSET
| 1,3
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EXAMPLE
| 6 has 4 positive divisors. The divisors of 6 are 1,2,3,6. The divisors of 6 that are coprime to 4 are 1 and 3. 3 is the largest of these; so a(6) = 3.
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MATHEMATICA
| Table[Select[Divisors[n], GCD[ #, Length[Divisors[n]]] == 1 &][[ -1]], {n, 1, 80}] - Stefan Steinerberger (stefan.steinerberger(AT)gmail.com), Mar 09 2008
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CROSSREFS
| Cf. A137927.
Sequence in context: A033706 A121890 A178231 * A090395 A168485 A123901
Adjacent sequences: A137923 A137924 A137925 * A137927 A137928 A137929
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KEYWORD
| nonn
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AUTHOR
| Leroy Quet Feb 23 2008
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EXTENSIONS
| More terms from Stefan Steinerberger (stefan.steinerberger(AT)gmail.com), Mar 09 2008
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