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A333326 Odd numbers k such that k is the product of 2 numbers greater than one, in two or more ways. 1
45, 63, 75, 81, 99, 105, 117, 135, 147, 153, 165, 171, 175, 189, 195, 207, 225, 231, 243, 245, 255, 261, 273, 275, 279, 285, 297, 315, 325, 333, 345, 351, 357, 363, 369, 375, 385, 387, 399, 405, 423, 425, 429, 435, 441, 455, 459, 465, 475 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Odd numbers that are not 1, a prime, the square or cube of a prime, or the product of two primes. - Robert Israel, Mar 19 2020

LINKS

Robert Israel, Table of n, a(n) for n = 1..10000

EXAMPLE

For n=2 the a(2) = 63 because 63 = 3 * 21 and 7 * 9.

MAPLE

select(t -> numtheory:-tau(t) >= 5, [seq(i, i=3..1000, 2)]); # Robert Israel, Mar 19 2020

MATHEMATICA

Select[2 * Range[250] + 1, DivisorSigma[0, #] > 4 &] (* Amiram Eldar, Mar 15 2020 *)

PROG

(PARI) forcomposite(n=4, 475, if(n%2 == 0, next()); if(numdiv(n) >= 5, print1(n, ", "))); \\ Joerg Arndt, Mar 15 2020

CROSSREFS

Cf. A005408, A058080, A226025.

Sequence in context: A140277 A242263 A242264 * A077646 A230577 A336555

Adjacent sequences:  A333323 A333324 A333325 * A333327 A333328 A333329

KEYWORD

nonn

AUTHOR

Dimitris Valianatos, Mar 15 2020

STATUS

approved

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Last modified May 15 02:21 EDT 2021. Contains 343909 sequences. (Running on oeis4.)