id:A115958 - OEIS Search Results

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Numbers n having exactly 4 distinct prime factors, the largest of which is greater than or equal to sqrt(n) (i.e. sqrt(n)-rough numbers with exactly 4 distinct prime factors).

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930, 1110, 1230, 1290, 1410, 1590, 1770, 1806, 1830, 1974, 2010, 2130, 2190, 2226, 2370, 2478, 2490, 2562, 2670, 2814, 2910, 2982, 3030, 3066, 3090, 3210, 3270, 3318, 3390, 3486, 3660, 3738, 3810, 3930, 4020, 4074, 4110, 4170, 4242, 4260, 4326, 4380 (list; graph; listen)

	OFFSET	`1,1`
	EXAMPLE	`3660 is in the sequence because it has 4 distinct prime factors` `(2, 3, 5 and 61) and 61>sqrt(3660).`
	MAPLE	`with(numtheory): a:=proc(n) if nops(factorset(n))=4 and factorset(n)[4]^2>=n then n else fi end: seq(a(n), n=1..4500);`
	CROSSREFS	`Cf. A115956, A115957, A115959, A115960, A115961.` `Sequence in context: A074889 A109184 A068651 this_sequence A158679 A035856 A093231` `Adjacent sequences: A115955 A115956 A115957 this_sequence A115959 A115960 A115961`
	KEYWORD	`nonn`
	AUTHOR	`Emeric Deutsch (deutsch(AT)duke.poly.edu), Feb 02 2006`

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Last modified December 19 21:04 EST 2009. Contains 171054 sequences.

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