id:A010693 - OEIS Search Results

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Period 2.

+0
6

2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3 (list; graph; listen)

	OFFSET	`0,1`
	COMMENT	`a(n) = smallest prime divisor of n!! for n >= 2. For biggest prime divisor of n!! see A139421. - Artur Jasinski (grafix(AT)csl.pl), Apr 21 2008`
	LINKS	`INRIA Algorithms Project, Encyclopedia of Combinatorial Structures 466`
	FORMULA	`a(n) = 5/2 - ((-1)^n)/2.` `a(n) = 2 + n mod 2 = A007395(n) + A000035(n). - Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), Mar 23 2005`
	MATHEMATICA	`Table[5/2 - (-1)^n/2, {n, 0, 100}] or a = {}; Do[b = First[First[FactorInteger[n!! ]]]; AppendTo[a, b], {n, 2, 1000}]; a - Artur Jasinski (grafix(AT)csl.pl), Apr 21 2008`
	CROSSREFS	`Cf. A139421.` `Adjacent sequences: A010690 A010691 A010692 this_sequence A010694 A010695 A010696` `Sequence in context: A066102 A036048 A117666 this_sequence A139713 A023524 A068639`
	KEYWORD	`nonn,easy`
	AUTHOR	`njas`

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Last modified October 7 14:39 EDT 2008. Contains 144666 sequences.

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