id:A069268 - OEIS Search Results

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Greatest common divisor of n! and n*(n+1)/2.

+0
4

1, 1, 6, 2, 15, 3, 28, 36, 45, 5, 66, 6, 91, 105, 120, 8, 153, 9, 190, 210, 231, 11, 276, 300, 325, 351, 378, 14, 435, 15, 496, 528, 561, 595, 630, 18, 703, 741, 780, 20, 861, 21, 946, 990, 1035, 23, 1128, 1176, 1225, 1275, 1326 (list; graph; listen)

	OFFSET	`1,3`
	FORMULA	`a(n) = if n>1 and n+1 is prime then n/2 else n*(n+1)/2.`
	CROSSREFS	`Cf. A000142, A000217, A000040.` `Cf. A090585, A090586.` `Adjacent sequences: A069265 A069266 A069267 this_sequence A069269 A069270 A069271` `Sequence in context: A080977 A095951 A116420 this_sequence A082155 A128225 A136398`
	KEYWORD	`nonn`
	AUTHOR	`Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), Apr 14 2002`

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Last modified October 12 13:44 EDT 2008. Contains 144830 sequences.

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