id:A074851 - OEIS Search Results

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Numbers n such that n and n+1 have 2 distinct prime factors.

+0
5

14, 20, 21, 33, 34, 35, 38, 39, 44, 45, 50, 51, 54, 55, 56, 57, 62, 68, 74, 75, 76, 85, 86, 87, 91, 92, 93, 94, 95, 98, 99, 111, 115, 116, 117, 118, 122, 123, 133, 134, 135, 141, 142, 143, 144, 145, 146, 147, 152, 158, 159, 160, 161, 171, 175, 176, 177, 183, 184 (list; graph; listen)

	OFFSET	`1,1`
	COMMENT	`20=2^25 21=37 hence 20 is in the sequence`
	FORMULA	`a(n) seems to be asymptotic to cnlog(n)^2 with c=0.13...`
	CROSSREFS	`Cf. A006549.` `Sequence in context: A092768 A006576 A083247 this_sequence A087678 A108874 A063848` `Adjacent sequences: A074848 A074849 A074850 this_sequence A074852 A074853 A074854`
	KEYWORD	`easy,nonn`
	AUTHOR	`Benoit Cloitre (benoit7848c(AT)orange.fr), Sep 10 2002`

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Last modified July 6 17:22 EDT 2008. Contains 140988 sequences.

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