id:A078496 - OEIS Search Results

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Smallest prime p such that p>n and 2*n-p is also prime.

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5, 7, 7, 11, 11, 11, 13, 17, 13, 19, 17, 17, 19, 23, 19, 31, 23, 23, 31, 29, 29, 31, 29, 31, 37, 41, 31, 43, 41, 37, 37, 41, 41, 43, 47, 41, 43, 53, 43, 67, 47, 47, 61, 53, 53, 61, 53, 59, 61, 59, 61, 67, 59, 61, 73, 71, 61, 79, 71, 67, 67, 71, 71, 73, 83, 71, 73, 83, 73, 79 (list; graph; listen)

	OFFSET	`4,1`
	COMMENT	`Suggested by Goldbach Conjecture.` `Values of q from A143697. This follows from the factorization n^2-k^2 = (n-k)(n+k).`
	LINKS	`P. CAMI, Table of n, a(n) for n = 4..60000`
	FORMULA	`n>3 integer; a(n)=min{p: p>n; p, 2*n-p are primes}`
	EXAMPLE	`a(11)=17`
	MATHEMATICA	`Table[p=n+1; q=2n-p; While[q>0&&!(PrimeQ[p]&&PrimeQ[q]), p++; q-- ]; p, {n, 4, 100}]`
	CROSSREFS	`Cf. A143697, A078587.` `a(n) = 2n - A078587(n)` `Cf. A082467` `Sequence in context: A137755 A053672 A087525 this_sequence A114521 A159482 A033932` `Adjacent sequences: A078493 A078494 A078495 this_sequence A078497 A078498 A078499`
	KEYWORD	`nonn`
	AUTHOR	`Serhat Sevki Dincer (sevki(AT)ug.bilkent.edu.tr), Nov 26 2002`
	EXTENSIONS	`Edited by N. J. A. Sloane (njas(AT)research.att.com), Jan 24 2009 at the sggestion of R. J. Mathar and T. D. Noe.`

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

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