OFFSET
1,1
COMMENTS
Numbers n such that A067742(n) >= 3.
The smallest number with 3 such factorizations is 840 = 28*30 = 24*35 = 21*40.
LINKS
Robert Israel, Table of n, a(n) for n = 1..10000
EXAMPLE
72 = 8 * 9 = 6 * 12, so it is in the sequence. 60 = 6 * 10, but the next closest factorization is 5 * 12 and 12 > 2*5, so 60 is not in the sequence.
MAPLE
filter:= proc(n) nops(select(t -> t^2 >= n/2 and t^2 <= 2*n, numtheory:-divisors(n)))>=3 end proc:
select(filter, [$1..2000]); # Robert Israel, Oct 21 2024
CROSSREFS
KEYWORD
nonn
AUTHOR
Franklin T. Adams-Watters, Apr 04 2010
STATUS
approved