id:A023898 - OEIS Search Results

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Divisor balance of n is an integer.

+0
3

1, 2, 4, 8, 9, 16, 18, 32, 36, 45, 64, 72, 81, 90, 98, 126, 128, 144, 162, 180, 225, 234, 256, 288, 294, 324, 360, 363, 396, 450, 484, 512, 539, 576, 625, 648, 720, 726, 729, 784, 882, 900, 1008, 1024, 1078, 1125, 1152, 1250, 1296, 1440, 1452, 1458, 1800 (list; graph; listen)

	OFFSET	`1,2`
	FORMULA	`\rm{Ibal}(n) = sum_{d divides n} {d \over \phi(d)}.`
	MATHEMATICA	`Select[ Range[ 2000 ], Function[ n, IntegerQ[ Plus @@ Map[ #/EulerPhi[ # ]&, Divisors[ n ] ] ] ] ]`
	CROSSREFS	`Cf. A023899.` `Sequence in context: A028982 A071601 A114400 this_sequence A125853 A080025 A152111` `Adjacent sequences: A023895 A023896 A023897 this_sequence A023899 A023900 A023901`
	KEYWORD	`nonn`
	AUTHOR	`Olivier Gerard (olivier.gerard(AT)gmail.com)`

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Last modified November 24 23:16 EST 2009. Contains 167481 sequences.

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