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A049198
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Squarefull numbers whose Euler totient function is squarefree.
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4
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4, 9, 18, 49, 98, 121, 242, 529, 961, 1058, 1849, 1922, 2209, 3481, 3698, 4418, 4489, 5041, 6241, 6889, 6962, 8978, 10082, 10609, 11449, 12482, 13778, 17161, 19321, 21218, 22898, 27889, 32041, 34322, 36481, 38642, 44521, 49729, 51529, 55778
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OFFSET
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1,1
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LINKS
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EXAMPLE
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a(27) = 13778 = 2*83*83 is divisible by a square, but phi(13778) = 6806 = 2*41*83 is squarefree.
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MATHEMATICA
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Abs[ MoebiusMu[ EulerPhi[ x ] ] ]=1 and Abs[ MoebiusMu[ x ] ]=0
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PROG
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(PARI) for(n=4, 10^7, if(issquarefree(n)==0 & issquarefree(eulerphi(n)), print1(n ", "))) /* Donovan Johnson, Jun 20 2012 */
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CROSSREFS
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KEYWORD
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nonn,easy
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AUTHOR
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STATUS
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approved
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