A345382 - OEIS

A345382

Numbers with exactly 3 semiprime divisors.

30, 36, 42, 66, 70, 72, 78, 100, 102, 105, 108, 110, 114, 130, 138, 144, 154, 165, 170, 174, 182, 186, 190, 195, 196, 200, 216, 222, 225, 230, 231, 238, 246, 255, 258, 266, 273, 282, 285, 286, 288, 290, 310, 318, 322, 324, 345, 354, 357, 366, 370, 374, 385, 392, 399, 400

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OFFSET

1,1

COMMENTS

Numbers of the form p*q*r or p^j*q^k, where p,q,r are prime and j,k >= 2. - Wesley Ivan Hurt, Oct 01 2021

LINKS

Table of n, a(n) for n=1..56.

EXAMPLE

42 is in the sequence since it has exactly 3 semiprime divisors: 6, 14 and 21.

CROSSREFS

Cf. A001358 (semiprimes).

Sequence in context: A350353 A357874 A325264 * A227680 A109426 A167325

Adjacent sequences: A345379 A345380 A345381 * A345383 A345384 A345385

KEYWORD

nonn

AUTHOR

Wesley Ivan Hurt, Jun 16 2021

STATUS

approved