Question Number 100290 by Harasanemanabrandah last updated on 26/Jun/20

Commented byRasheed.Sindhi last updated on 26/Jun/20

^• If n is multiple of 3 then 3^n +n^3 is obviously composite (3 ∣ 3^n +n^3 ) ^• If n is odd then 3^n +n^3 is composite ( 2 ∣ 3^n +n^3 ) Hence for n∈{3,6,9,...}∪{1,3,5,...} the given expression is composite.