id:A064830 - OEIS Search Results

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a(n) = GCD(n, prime(n)^2 - 1).

+0
4

1, 2, 3, 4, 5, 6, 1, 8, 3, 10, 1, 12, 1, 14, 3, 8, 1, 6, 1, 20, 3, 2, 1, 24, 1, 2, 3, 4, 1, 6, 1, 8, 3, 2, 5, 12, 1, 2, 3, 8, 1, 42, 1, 4, 9, 2, 1, 48, 1, 10, 3, 4, 1, 18, 1, 8, 3, 2, 1, 60, 1, 2, 63, 16, 13, 6, 1, 4, 3, 70, 1, 72, 1, 2, 15, 4, 1, 6, 1, 80, 3, 2, 1, 84, 5, 2, 3, 8, 1, 6, 13, 4, 3, 2 (list; graph; listen)

	OFFSET	`1,2`
	EXAMPLE	`A000040(20) = 71, GCD(20, (71-1)(71+1)) = 10 GCD(2, 7*72) = 20 = a(20).`
	MATHEMATICA	`Table[ GCD[n, Prime[n]^2 - 1], {n, 1, 100} ]`
	CROSSREFS	`Cf. A000040.` `Sequence in context: A125934 A125935 A138776 this_sequence A106608 A030106 A037894` `Adjacent sequences: A064827 A064828 A064829 this_sequence A064831 A064832 A064833`
	KEYWORD	`nonn`
	AUTHOR	`Reinhard Zumkeller (reinhard.zumkeller(AT)lhsystems.com), Oct 23 2001`

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Last modified July 4 18:25 EDT 2008. Contains 140886 sequences.

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