id:A065872 - OEIS Search Results

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Numbers n such that usigma(n) - 1 is a prime (cf. A034448).

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2, 3, 5, 6, 7, 10, 11, 12, 13, 14, 15, 17, 18, 19, 20, 21, 23, 26, 29, 30, 31, 33, 34, 35, 37, 38, 40, 41, 43, 44, 45, 46, 47, 48, 51, 53, 54, 55, 56, 57, 58, 59, 61, 63, 65, 67, 68, 71, 72, 73, 74, 75, 78, 79, 80, 83, 85, 86, 88, 89, 90, 93, 96, 97, 98, 101, 103, 105, 107 (list; graph; listen)

	OFFSET	`1,1`
	MATHEMATICA	`f[n_] := Block[ {a = FactorInteger[n], k = l = s = 1}, l = Length[a]; While[k <= l, s = s * (a[[k, 1]]^a[[k, 2]] + 1); k++ ]; Return[s]]; Select[ Range[200], PrimeQ[ f[ # ] - 1] & ]`
	CROSSREFS	`Cf. A034448.` `Sequence in context: A007916 A052485 A109421 this_sequence A028741 A119316 A102750` `Adjacent sequences: A065869 A065870 A065871 this_sequence A065873 A065874 A065875`
	KEYWORD	`nonn`
	AUTHOR	`Robert G. Wilson v (rgwv(AT)rgwv.com), Dec 07 2001`

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Last modified August 19 23:53 EDT 2008. Contains 142930 sequences.

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