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A115956 Numbers n having exactly 2 distinct prime factors, the largest of which is greater than or equal to sqrt(n) (i.e., sqrt(n)-rough numbers with exactly 2 distinct prime factors). 5
6, 10, 14, 15, 20, 21, 22, 26, 28, 33, 34, 35, 38, 39, 44, 46, 51, 52, 55, 57, 58, 62, 65, 68, 69, 74, 76, 77, 82, 85, 86, 87, 88, 91, 92, 93, 94, 95, 99, 104, 106, 111, 115, 116, 117, 118, 119, 122, 123, 124, 129, 133, 134, 136, 141, 142, 143, 145, 146, 148, 152, 153 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..62.

EXAMPLE

20 is in the sequence because it has 2 distinct prime factors (2 and 5) and 5 > sqrt(20).

MAPLE

with(numtheory): a:=proc(n) if nops(factorset(n))=2 and factorset(n)[2]^2>=n then n else fi end: seq(a(n), n=1..170);

CROSSREFS

Cf. A115957, A115958, A115959, A115960, A115961.

Sequence in context: A082092 A069116 A063763 * A066073 A339438 A268376

Adjacent sequences:  A115953 A115954 A115955 * A115957 A115958 A115959

KEYWORD

nonn

AUTHOR

Emeric Deutsch, Feb 02 2006

STATUS

approved

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Last modified March 7 10:14 EST 2021. Contains 341869 sequences. (Running on oeis4.)