id:A128234 - OEIS Search Results

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Values of n such that the average of p(n) and p(p(n)), where p(k) denotes the k-th prime, is prime.

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8, 9, 11, 12, 19, 23, 28, 62, 64, 68, 71, 85, 95, 104, 114, 115, 131, 134, 175, 178, 181, 182, 200, 216, 240, 246, 247, 250, 266, 276, 277, 316, 346, 372, 382, 421, 429, 438, 440, 444, 445, 458, 469, 485, 494, 511, 518, 541, 543, 566, 568, 594, 596, 601, 604 (list; graph; listen)

	OFFSET	`2,1`
	EXAMPLE	`9 is in the sequence because p(9)=23, p(23)=83 and (23+83)/2 is prime.`
	MAPLE	`a:=proc(n) if isprime((ithprime(n)+ithprime(ithprime(n)))/2)=true then n else fi end: seq(a(n), n=2..800);`
	CROSSREFS	`Cf. A128233.` `Adjacent sequences: A128231 A128232 A128233 this_sequence A128235 A128236 A128237` `Sequence in context: A109936 A114460 A120201 this_sequence A087668 A120176 A048590`
	KEYWORD	`nonn`
	AUTHOR	`Emeric Deutsch (deutsch(AT)duke.poly.edu), Feb 20 2007`

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Last modified October 7 08:31 EDT 2008. Contains 144667 sequences.

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