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A289555
Numbers that are not the product of two distinct composite numbers (A002808).
2
1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 25, 26, 27, 28, 29, 30, 31, 33, 34, 35, 37, 38, 39, 41, 42, 43, 44, 45, 46, 47, 49, 50, 51, 52, 53, 55, 57, 58, 59, 61, 62, 63, 65, 66, 67, 68, 69, 70, 71, 73, 74, 75, 76, 77
OFFSET
1,2
EXAMPLE
Number 24 is not in the sequence because 24 = 4 * 6.
PROG
(Magma) [n: n in [1..1000] | (#PrimeDivisors(n) eq 1 and NumberOfDivisors(n) lt 6) or (#PrimeDivisors(n) eq 2 and NumberOfDivisors(n) lt 8) or (#PrimeDivisors(n) ge 3 and NumberOfDivisors(n) lt 12) ]
CROSSREFS
Complement of A289554.
Cf. A246716 (with two distinct primes), A008578 (with two distinct nonprimes), A289553 (with two distinct noncomposites).
Sequence in context: A064598 A366187 A364354 * A354808 A048242 A272076
KEYWORD
nonn
AUTHOR
Jaroslav Krizek, Jul 07 2017
STATUS
approved