id:A069901 - OEIS Search Results

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Smallest prime factor of n-th triangular number.

+0
5

1, 3, 2, 2, 3, 3, 2, 2, 3, 5, 2, 2, 7, 3, 2, 2, 3, 3, 2, 2, 3, 11, 2, 2, 5, 3, 2, 2, 3, 3, 2, 2, 3, 5, 2, 2, 19, 3, 2, 2, 3, 3, 2, 2, 3, 23, 2, 2, 5, 3, 2, 2, 3, 3, 2, 2, 3, 29, 2, 2, 31, 3, 2, 2, 3, 3, 2, 2, 3, 5, 2, 2, 37, 3, 2, 2, 3, 3, 2, 2, 3, 41, 2, 2, 5, 3, 2, 2 (list; graph; listen)

	OFFSET	`1,2`
	COMMENT	`a(n) = A020639(A000217(n)).`
	EXAMPLE	`A000217(10) = 10(10+1)/2 = 55 = 511, therefore a(10) = 5.`
	CROSSREFS	`Cf. A069902, A069903, A069904.` `Sequence in context: A122028 A049234 A125504 this_sequence A075392 A115039 A032536` `Adjacent sequences: A069898 A069899 A069900 this_sequence A069902 A069903 A069904`
	KEYWORD	`nonn`
	AUTHOR	`Reinhard Zumkeller (reinhard.zumkeller(AT)lhsystems.com), Apr 10, 2002`

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Last modified July 6 17:22 EDT 2008. Contains 140988 sequences.

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