id:A117096 - OEIS Search Results

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Numbers n such that nextprime(2*n)<2*nextprime(n) (if p is prime then nextprime(p)=p).

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1, 6, 8, 9, 14, 15, 18, 20, 21, 24, 25, 26, 30, 32, 33, 34, 35, 36, 38, 39, 44, 48, 49, 50, 51, 54, 55, 56, 62, 63, 64, 65, 68, 69, 74, 75, 76, 77, 78, 80, 81, 84, 85, 86, 90, 91, 92, 93, 94, 95, 96, 98, 99, 104, 105, 110, 111, 114, 115, 116, 117, 118, 119, 120, 121, 122, 123 (list; graph; listen)

	OFFSET	`1,2`
	COMMENT	`if p is prime and nextprime(pn)<nextprime(p)nextprime(n) then n is composite`
	EXAMPLE	`nextprime(26)=13 and nextprime(2)nextprime(6)=2*7=14 then 6 is member because 13<14`
	PROGRAM	`(PARI) for(i=1, 150, if(nextprime(2i)<nextprime(2)nextprime(i), print1(i, ", ")))`
	CROSSREFS	`Sequence in context: A030725 A043720 A161982 this_sequence A067812 A047394 A085725` `Adjacent sequences: A117093 A117094 A117095 this_sequence A117097 A117098 A117099`
	KEYWORD	`easy,nonn`
	AUTHOR	`Mohammed Bouayoun (mohammed.bouayoun(AT)sanef.com), Apr 18 2006`

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Last modified December 16 17:18 EST 2009. Contains 170825 sequences.

AT&T Labs Research