id:A139421 - OEIS Search Results

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a(1)=1; for n>1, a(n) = largest prime divisor of n!!.

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1, 2, 3, 2, 5, 3, 7, 3, 7, 5, 11, 5, 13, 7, 13, 7, 17, 7, 19, 7, 19, 11, 23, 11, 23, 13, 23, 13, 29, 13, 31, 13, 31, 17, 31, 17, 37, 19, 37, 19, 41, 19, 43, 19, 43, 23, 47, 23, 47, 23, 47, 23, 53, 23, 53, 23, 53, 29, 59, 29, 61, 31, 61, 31, 61, 31, 67, 31, 67, 31, 71, 31, 73, 37 (list; graph; listen)

	OFFSET	`1,2`
	MATHEMATICA	`a = {}; Do[b = First[Last[FactorInteger[n!! ]]]; AppendTo[a, b], {n, 2, 100}]; a`
	CROSSREFS	`Cf. A010693.` `Sequence in context: A039635 A164858 A081812 this_sequence A165500 A072505 A095163` `Adjacent sequences: A139418 A139419 A139420 this_sequence A139422 A139423 A139424`
	KEYWORD	`nonn`
	AUTHOR	`Artur Jasinski (grafix(AT)csl.pl), Apr 21 2008`

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Last modified November 25 20:09 EST 2009. Contains 167514 sequences.

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