id:A158287 - OEIS Search Results

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Composite RMS numbers: composite numbers c such that root mean square of divisors of c is an integer.

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287, 1673, 3055, 6665, 9545, 9799, 9855, 21385, 26095, 34697, 46655, 66815, 68593, 68985, 125255, 155287, 182665, 242879, 273265, 380511, 391345, 404055, 421655, 627215, 730145, 814463, 823537, 876785, 1069895, 1087009, 1166399, 1204281 (list; graph; listen)

	OFFSET	`1,1`
	COMMENT	`a(n) = composite number c (A002808), iff sqrt(sigma_2(c)/tau(c) = sqrt(A001157(c)/A000005(c)= k, for k = natural numbers (A000027). Prime RMS numbers (NSW primes) in A088165.`
	EXAMPLE	`a(1) = 287, sqrt(A001157(287)/A000005(287)= sqrt(84100/4) = 145, number 145 is integer.`
	CROSSREFS	`Cf. A001157, A000005, A088165.` `Sequence in context: A063362 A159949 A158252 this_sequence A112245 A011817 A035882` `Adjacent sequences: A158284 A158285 A158286 this_sequence A158288 A158289 A158290`
	KEYWORD	`nonn`
	AUTHOR	`Jaroslav Krizek (jaroslav.krizek(AT)atlas.cz), Mar 15 2009`

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Last modified November 25 20:09 EST 2009. Contains 167514 sequences.

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