猴哥112第69题.怎么是12呢?难道不是4*3+4*3*1+1Howmanypositiveintegerscanbeexpressedasaproductoftwoormoreoftheprimenumber5,7,11,and13ifnooneproductistoincludethesameprimefactormorethanonce?

Question

猴哥112 第69题.怎么是12呢?难道不是4*3+4*3*1+1
How many positive integers can be expressed as a product of two or more of the prime number 5,7,11,and 13 if no one product is to include the same prime factor more than once?

Answer 1

5,7
5,11
5,13
7,11
7,13
11,13
5,7,11
5,7,13
5,11,13
7,11,13
5,7,11,13