Question 1209410
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See the explicit solution, found/produced by artificial intelligence (AI) 
as the response to my request under this link


https://www.google.com/search?q=Let+S+be+the+set+of+all+real+numbers+of+the+form+(a_1)%2F(3)+%2B+(a_2)%2F(3%5E2)+%2B+(a_3)%2F(3%5E3)+%2B+...+where+(a_i)+is+equal+to+either+0%2C+1%2C+or+2+for+each+i.+(a)+Is+the+number+1%2F4+in+the+set+S%3F+(b)+Is+the+number+1%2F7+in+the+set+S%3F&rlz=1C1CHBF_enUS1071US1071&oq=Let+S+be+the+set+of+all+real+numbers+of+the+form++(a_1)%2F(3)+%2B+(a_2)%2F(3%5E2)+%2B+(a_3)%2F(3%5E3)+%2B+...++where+(a_i)+is+equal+to+either+0%2C+1%2C+or+2+for+each+i.++(a)+Is+the+number+1%2F4+in+the+set+S%3F+++(b)+Is+the+number+1%2F7+in+the+set+S%3F&gs_lcrp=EgZjaHJvbWUyBggAEEUYOdIBCTE5MjhqMGoxNagCCLACAQ&sourceid=chrome&ie=UTF-8