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URL: https://oeis.org/A378480

⇱ A378480 - OEIS

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A378480
Products of 3 distinct prime numbers (or sphenics) that are deficient.
1
105, 110, 130, 154, 165, 170, 182, 190, 195, 230, 231, 238, 255, 266, 273, 285, 286, 290, 310, 322, 345, 357, 370, 374, 385, 399, 406, 410, 418, 429, 430, 434, 435, 442, 455, 465, 470, 483, 494, 506, 518, 530, 555, 561, 574, 590, 595, 598, 602, 609, 610, 615, 627, 638, 645, 646, 651, 658, 663, 665
OFFSET
1,1
EXAMPLE
105 is a term because 105=3*5*7 is the product of three distinct primes and it is larger than the sum of its proper divisors (1+3+5+7+15+21+35=87).
110 is a term because 110=2*5*11 is the product of three distinct primes and it is larger than the sum of its proper divisors (1+2+5+10+11+22+55=106).
MATHEMATICA
q[n_] := Module[{f = FactorInteger[n]}, f[[;; , 2]] == {1, 1, 1} && Times @@ (1 + 1/f[[;; , 1]]) < 2]; Select[Range[1000], q] (* Amiram Eldar, Nov 28 2024 *)
CROSSREFS
Intersection of A005100 and A007304.
Sequence in context: A090053 A096093 A386501 * A179142 A039553 A135999
KEYWORD
nonn
AUTHOR
Massimo Kofler, Nov 28 2024
STATUS
approved