id:A078542 - OEIS Search Results

Search: id:A078542

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Unbalanced composite numbers.

+0
2

4, 8, 9, 10, 16, 18, 20, 21, 22, 24, 25, 26, 27, 28, 32, 33, 34, 36, 38, 39, 40, 44, 45, 46, 48, 49, 50, 51, 52, 54, 55, 57, 58, 60, 62, 63, 64, 65, 66, 68, 69, 72, 74, 75, 76, 77, 80, 81, 82, 84, 85, 86, 87, 88, 90, 91, 92, 93, 94, 95, 96, 98, 99, 100, 102, 104, 106, 108 (list; graph; listen)

	OFFSET	`1,1`
	EXAMPLE	`n=46=2.23 and sigma[46]/phi[46]=72/22 is not an integer.`
	MATHEMATICA	`Do[s=DivisorSigma[1, n]/EulerPhi[n]; If[ !IntegerQ[s]&&!PrimeQ[n], Print[n]], {n, 1, 256}]`
	CROSSREFS	`Cf. A020492, A078538, A078539, A078540.` `Sequence in context: A080970 A125493 A094906 this_sequence A124982 A073042 A094349` `Adjacent sequences: A078539 A078540 A078541 this_sequence A078543 A078544 A078545`
	KEYWORD	`nonn`
	AUTHOR	`Labos E. (labos(AT)ana.sote.hu), Dec 04 2002`

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Last modified August 29 17:54 EDT 2008. Contains 143238 sequences.

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