id:A076820 - OEIS Search Results

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Second-largest distinct prime dividing n (or 1 if n is a power of a prime).

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1, 1, 1, 1, 1, 2, 1, 1, 1, 2, 1, 2, 1, 2, 3, 1, 1, 2, 1, 2, 3, 2, 1, 2, 1, 2, 1, 2, 1, 3, 1, 1, 3, 2, 5, 2, 1, 2, 3, 2, 1, 3, 1, 2, 3, 2, 1, 2, 1, 2, 3, 2, 1, 2, 5, 2, 3, 2, 1, 3, 1, 2, 3, 1, 5, 3, 1, 2, 3, 5, 1, 2, 1, 2, 3, 2, 7, 3, 1, 2, 1, 2, 1, 3, 5, 2, 3, 2, 1, 3, 7, 2, 3, 2, 5, 2, 1, 2, 3, 2, 1, 3, 1, 2, 5 (list; graph; listen)

	OFFSET	`1,6`
	COMMENT	`The 3rd-largest is 1 except 2 at 30, 42, 60, 66, 70, ...`
	FORMULA	`If p_1 < p_2 < ... <p_{k-1} < p_k are the distinct primes dividing n then a(n) = p_{k-1}.`
	CROSSREFS	`Cf. A006530.` `Sequence in context: A051265 A008647 A036475 this_sequence A082068 A082069 A136755` `Adjacent sequences: A076817 A076818 A076819 this_sequence A076821 A076822 A076823`
	KEYWORD	`nonn,easy`
	AUTHOR	`R. K. Guy (rkg(AT)cpsc.ucalgary.ca), Nov 19 2002`
	EXTENSIONS	`More terms from Jason Earls (zevi_35711(AT)yahoo.com) and John W. Layman (layman(AT)math.vt.edu), Nov 21 2002`

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Last modified November 30 22:12 EST 2008. Contains 150989 sequences.

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