id:A103289 - OEIS Search Results

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Numbers n such that both sigma(n)>=2n-1 and sigma(n+1)>=2(n+1)-1.

+0
4

1, 4095, 5775, 5984, 7424, 11024, 21735, 21944, 26144, 27404, 39375, 43064, 49664, 56924, 58695, 61424, 69615, 70784, 76544, 77175, 79695, 81080, 81675, 82004, 84524, 84644, 89775, 91664, 98175, 103455, 104895, 106784, 109395, 111824 (list; graph; listen)

	OFFSET	`1,2`
	COMMENT	`A004125(n) is less than A004125(n-1) and A004125(n+1) iff n belongs to A023196 but not to A103289.`
	FORMULA	`Such numbers n that both n and n+1 are in A103288. Union of sequences A096399 and {2^m-1} for m in A103291.`
	PROGRAM	`(PARI) for(i=1, 1000000, if(sigma(i)>=2i-1 && sigma(i+1)>=2i+1, print(i)));`
	CROSSREFS	`Cf. A103288, A096399, A103291, A004125, A023196.` `Sequence in context: A063889 A024022 A145591 this_sequence A038463 A043452 A075952` `Adjacent sequences: A103286 A103287 A103288 this_sequence A103290 A103291 A103292`
	KEYWORD	`nonn`
	AUTHOR	`Max Alekseyev (maxale(AT)gmail.com), Jan 28 2005`

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

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