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Search: id:A055971
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| A055971 |
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Numbers n such that n | Sigma(n) - d(n) - Phi(n) and n is not a prime or twice a prime, where d(n) is the number of divisors of n. |
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+0
1
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| 1, 198, 294, 20280, 195320, 1782240, 3038720, 12190720
(list; graph; listen)
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OFFSET
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1,2
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MATHEMATICA
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Do[ If[ And[ !PrimeQ[ n ], !PrimeQ[ n/2 ] ], If[ Mod[ DivisorSigma[ 1, n ]-DivisorSigma[ 0, n ]- EulerPhi[ n ], n ]==0, Print[ n ] ] ], {n, 1, 10^8} ]
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CROSSREFS
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Adjacent sequences: A055968 A055969 A055970 this_sequence A055972 A055973 A055974
Sequence in context: A025375 A031512 A025366 this_sequence A075293 A083264 A066218
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KEYWORD
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easy,nonn
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AUTHOR
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Robert G. Wilson v (rgwv(AT)rgwv.com), Jul 19 2000
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