id:A125640 - OEIS Search Results

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Primitive doubly abundant numbers - doubly abundant numbers that are not the multiple of another doubly abundant number.

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24, 30, 42, 54, 66, 78, 102, 114, 138, 140, 174, 176, 186, 222, 224, 246, 258, 282, 308, 318, 340, 354, 364, 366, 380, 402, 426, 438, 440, 474, 476, 498, 520, 532, 534, 580, 582, 606, 618, 642, 644, 654, 678, 704, 762, 786, 812, 822, 834, 852, 868, 894, 896 (list; graph; listen)

	OFFSET	`1,1`
	COMMENT	`Are there infinitely many primitive doubly abundant numbers?`
	EXAMPLE	`42 is a primitive doubly abundant number because it is abundant (s(42) = 54), the sum of its proper divisors is abundant (s(54) = 66) and no divisor of 42 is doubly abundant.`
	CROSSREFS	`Cf. A005101, A125639.` `Sequence in context: A030626 A125639 A076496 this_sequence A141545 A106682 A135045` `Adjacent sequences: A125637 A125638 A125639 this_sequence A125641 A125642 A125643`
	KEYWORD	`nonn`
	AUTHOR	`Gabriel Cunningham (gabriel.cunningham(AT)gmail.com), Nov 28 2006`

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Last modified December 17 13:29 EST 2009. Contains 170826 sequences.

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