A378480 Products of 3 distinct primes numbers (or sphenics) that are deficient.

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

Links

Table of n, a(n) for n=1..60.

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: A090055 A090053 A096093 * A179142 A039553 A135999

Adjacent sequences: A378477 A378478 A378479 * A378481 A378482 A378483

Keyword

nonn

Author

Massimo Kofler, Nov 28 2024

Status

approved