id:A069902 - OEIS Search Results

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Largest prime factor of n-th triangular number n(n+1)/2.

+0
5

3, 3, 5, 5, 7, 7, 3, 5, 11, 11, 13, 13, 7, 5, 17, 17, 19, 19, 7, 11, 23, 23, 5, 13, 13, 7, 29, 29, 31, 31, 11, 17, 17, 7, 37, 37, 19, 13, 41, 41, 43, 43, 11, 23, 47, 47, 7, 7, 17, 17, 53, 53, 11, 11, 19, 29, 59, 59, 61, 61, 31, 7, 13, 13, 67 (list; graph; listen)

	OFFSET	`2,1`
	COMMENT	`a(n) = A006530(A000217(n)).`
	EXAMPLE	`A000217(9) = 9(9+1)/2 = 55 = 33*5, therefore a(9) = 5.`
	CROSSREFS	`Cf. A069901, A069903, A069904. Essentially the same as A074399.` `Sequence in context: A004649 A002374 A110560 this_sequence A085779 A078936 A061794` `Adjacent sequences: A069899 A069900 A069901 this_sequence A069903 A069904 A069905`
	KEYWORD	`nonn`
	AUTHOR	`Reinhard Zumkeller (reinhard.zumkeller(AT)lhsystems.com), Apr 10, 2002`

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Last modified July 25 07:41 EDT 2008. Contains 142293 sequences.

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