id:A103288 - OEIS Search Results

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Numbers n such that sigma(n) >= 2n-1 (union of perfect, abundant and least deficient numbers).

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1, 2, 4, 6, 8, 12, 16, 18, 20, 24, 28, 30, 32, 36, 40, 42, 48, 54, 56, 60, 64, 66, 70, 72, 78, 80, 84, 88, 90, 96, 100, 102, 104, 108, 112, 114, 120, 126, 128, 132, 138, 140, 144, 150, 156, 160, 162, 168, 174, 176, 180, 186, 192, 196, 198, 200, 204, 208, 210, 216, 220 (list; graph; listen)

	OFFSET	`1,2`
	COMMENT	`If the only least deficient numbers are the powers of 2 (open problem) then this sequence is a union of A023196 and A000079.`
	FORMULA	`Such n that A004125(n) <= A004125(n-1)`
	PROGRAM	`(PARI) for(n=1, 1000, if(sigma(n)>=2*n-1, print(n)));`
	CROSSREFS	`Cf. A023196, A023197, A023198, A023199, A000079, A004125.` `Sequence in context: A090404 A058825 A087086 this_sequence A125225 A092903 A005153` `Adjacent sequences: A103285 A103286 A103287 this_sequence A103289 A103290 A103291`
	KEYWORD	`nonn`
	AUTHOR	`Max Alekseyev (maxale(AT)gmail.com), Jan 28 2005`

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Last modified November 27 14:50 EST 2009. Contains 167570 sequences.

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