id:A023897 - OEIS Search Results

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sigma_1(n) / phi(n) for balanced numbers.

+0
7

1, 3, 2, 6, 7, 4, 3, 9, 2, 8, 5, 6, 7, 4, 7, 10, 5, 12, 4, 9, 10, 3, 4, 14, 10, 8, 6, 13, 9, 8, 5, 15, 7, 2, 6, 8, 4, 5, 12, 6, 7, 10, 10, 11, 14, 12, 9, 4, 3, 4, 12, 9, 4, 4, 7, 5, 7, 10, 3, 5, 4, 13, 14, 12, 10, 9, 10, 8, 7, 4, 8, 6, 18, 9, 3, 8, 13, 8, 15, 15, 8, 3, 14, 9, 10, 8, 8, 10, 5, 7, 8, 11, 6, 11, 13, 6 (list; graph; listen)

	OFFSET	`1,2`
	COMMENT	`sigma_1(n) is the sum of the divisors of n [same as sigma(n)] (A000203).`
	MATHEMATICA	`Select[ Array[ DivisorSigma[ 1, # ]/EulerPhi[ # ]&, 20000 ], IntegerQ ]`
	PROGRAM	`(MAGMA) [ q: n in [1..20000] \| r eq 0 where q, r is Quotrem(SumOfDivisors(n), EulerPhi(n)) ]; [From Klaus Brockhaus (klaus-brockhaus(AT)t-online.de), Nov 09 2008]`
	CROSSREFS	`Cf. A000010, A000203, A020492.` `Sequence in context: A087237 A102004 A125764 this_sequence A100527 A063946 A154441` `Adjacent sequences: A023894 A023895 A023896 this_sequence A023898 A023899 A023900`
	KEYWORD	`nonn`
	AUTHOR	`Olivier Gerard (olivier.gerard(AT)gmail.com)`

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Last modified November 24 19:42 EST 2009. Contains 167435 sequences.

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