id:A089306 - OEIS Search Results

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Smallest prime of the form n + (n+1)+ (n+2)+...+(n+k), or 0 if no such prime exists.

+0
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3, 2, 3, 0, 5, 13, 7, 17, 19, 0, 11, 0, 13, 29, 31, 0, 17, 37, 19, 41, 43, 0, 23, 0, 0, 53, 0, 0, 29, 61, 31, 0, 67, 0, 71, 73, 37, 0, 79, 0, 41, 0, 43, 89, 0, 0, 47, 97, 0, 101, 103, 0, 53, 109, 0, 113, 0, 0, 59, 0, 61, 0, 127, 0, 131, 0, 67, 137, 139, 0, 71, 0, 73, 149, 151, 0, 0 (list; graph; listen)

	OFFSET	`1,1`
	COMMENT	`If n is prime a(n) = n, If n is not a prime but 2n+1 is a prime then a(n) = 2n+1 else a(n) = 0, as the difference of two triangular numbers is composite if the indices differ by more than 2. r(r+1)/2 - s(s+1)/2 is composite if r-s >2.`
	CROSSREFS	`Sequence in context: A093347 A134676 A103491 this_sequence A086099 A048967 A166592` `Adjacent sequences: A089303 A089304 A089305 this_sequence A089307 A089308 A089309`
	KEYWORD	`nonn`
	AUTHOR	`Amarnath Murthy (amarnath_murthy(AT)yahoo.com), Nov 01 2003`
	EXTENSIONS	`More terms from David Wasserman (wasserma(AT)spawar.navy.mil), Sep 09 2005`

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

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