A107745 - OEIS

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A107745

Smallest prime factor of 6*n-1.

5, 11, 17, 23, 29, 5, 41, 47, 53, 59, 5, 71, 7, 83, 89, 5, 101, 107, 113, 7, 5, 131, 137, 11, 149, 5, 7, 167, 173, 179, 5, 191, 197, 7, 11, 5, 13, 227, 233, 239, 5, 251, 257, 263, 269, 5, 281, 7, 293, 13, 5, 311, 317, 17, 7, 5, 11, 347, 353, 359, 5, 7, 13, 383, 389, 5, 401, 11 (list; graph; refs; listen; history; internal format)

	OFFSET	`1,1`
	COMMENTS	`If 6n-1 is prime, a(n) = 6n-1. Cf. A107744 Smallest prime factor of 6*n+1, A107746 Values of n such that A107745(n)>A107746(n), A107747 Values of n such that A107745(n) < A107746(n).`
	FORMULA	`a(n) = A020639(6n-1). - R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Jan 23 2007`
	MATHEMATICA	`a[n_]:= FactorInteger[6*n - 1][[1, 1]]; Array[a, 100]`
	CROSSREFS	`Cf. A107744, A107746, A107747.` `Cf. A111863.` `Sequence in context: A190334 A123083 A157847 * A111863 A043389 A000966` `Adjacent sequences: A107742 A107743 A107744 * A107746 A107747 A107748`
	KEYWORD	`nonn`
	AUTHOR	`Zak Seidov (zakseidov(AT)yahoo.com), May 23 2005`

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Last modified February 16 07:39 EST 2012. Contains 205881 sequences.