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A055971 Numbers n such that n | (sigma(n) - d(n) - phi(n)) and n is not a prime or twice a prime. 1
1, 198, 294, 20280, 195320, 1782240, 3038720, 12190720 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,2
LINKS
MATHEMATICA
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} ]
CROSSREFS
Cf. A000005 (d(n)), A000010 (phi), A000203 (sigma).
Sequence in context: A248534 A334403 A238230 * A075293 A083264 A202526
KEYWORD
easy,nonn
AUTHOR
Robert G. Wilson v, Jul 19 2000
STATUS
approved

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Last modified March 28 18:04 EDT 2024. Contains 371254 sequences. (Running on oeis4.)