id:A117183 - OEIS Search Results

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a(n) = smallest prime dividing n-th non-squarefree positive integer.

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2, 2, 3, 2, 2, 2, 2, 2, 5, 3, 2, 2, 2, 2, 2, 3, 2, 7, 2, 2, 2, 2, 2, 3, 2, 2, 2, 3, 2, 2, 3, 2, 2, 2, 2, 2, 2, 3, 2, 2, 2, 2, 2, 3, 2, 11, 2, 5, 2, 2, 2, 3, 2, 2, 2, 3, 2, 2, 2, 3, 2, 2, 2, 2, 2, 13, 3, 2, 5, 2, 2, 2, 2, 3, 2, 2, 2, 2, 2, 3, 2, 2, 2, 2, 2, 3, 2, 2, 2, 2, 2, 2, 3, 2, 5, 2, 2, 2, 2, 2, 3, 2, 2, 2 (list; graph; listen)

	OFFSET	`1,1`
	FORMULA	`A020639(A013929(n))`
	EXAMPLE	`12, the 4th non-squarefree positive integer, is 2^2 * 3. 2 is the smallest prime dividing 12. So a(4) = 2.`
	MAPLE	`with(numtheory): a:=proc(n) if mobius(n)=0 then op(1, factorset(n)) fi end: seq(a(n), n=1..345); - (Deutsch)`
	MATHEMATICA	Needs["NumberTheory`NumberTheoryFunctions`"]; FactorInteger[ # ][[1, 1]] & /@ Select[ Range@252, !SquareFreeQ@# &] (Robert G. Wilson v)
	CROSSREFS	`Cf. A115074, A115090, A013929, A020639.` `Sequence in context: A031284 A064569 A145989 this_sequence A071187 A134852 A071188` `Adjacent sequences: A117180 A117181 A117182 this_sequence A117184 A117185 A117186`
	KEYWORD	`nonn`
	AUTHOR	`Leroy Quet (qq-quet(AT)mindspring.com), Mar 01 2006`
	EXTENSIONS	`More terms from Emeric Deutsch (deutsch(AT)duke.poly.edu) and Robert G. Wilson v (rgwv(at)rgwv.com), Mar 06 2006`

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Last modified November 18 20:14 EST 2008. Contains 147244 sequences.

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