A115958 - OEIS

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A115958

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).

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; refs; listen; history; internal format)

	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: A109184 A068651 A175726 * A158679 A035856 A093231` `Adjacent sequences: A115955 A115956 A115957 * A115959 A115960 A115961`
	KEYWORD	`nonn`
	AUTHOR	`Emeric Deutsch (deutsch(AT)duke.poly.edu), Feb 02 2006`

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Last modified February 17 02:48 EST 2012. Contains 205978 sequences.