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A289553 Numbers n that are not the product of two distinct noncomposite numbers (A008578). 1
1, 4, 8, 9, 12, 16, 18, 20, 24, 25, 27, 28, 30, 32, 36, 40, 42, 44, 45, 48, 49, 50, 52, 54, 56, 60, 63, 64, 66, 68, 70, 72, 75, 76, 78, 80, 81, 84, 88, 90, 92, 96, 98, 99, 100, 102, 104, 105, 108, 110, 112, 114, 116, 117, 120, 121, 124, 125, 126, 128, 130, 132 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Numbers n such that tau(n) = A000005(n) is not equal to 2*omega(n) = 2*A001221(n).

LINKS

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

EXAMPLE

Number 6 is not in the sequence because 6 = 2 * 3.

PROG

(MAGMA) [n: n in [1..1000] | NumberOfDivisors(n) ne 2*#PrimeDivisors(n)]

CROSSREFS

Complement of A167171.

Cf. A246716 (with two distinct primes), A008578 (with two distinct nonprimes), A289555 (with two distinct composites).

Sequence in context: A020671 A171598 A259241 * A013929 A162966 A190641

Adjacent sequences:  A289550 A289551 A289552 * A289554 A289555 A289556

KEYWORD

nonn

AUTHOR

Jaroslav Krizek, Jul 07 2017

STATUS

approved

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Last modified February 28 23:19 EST 2020. Contains 332353 sequences. (Running on oeis4.)