Answer :

celeneoneill
you have to times each number by 7. so the next three numbers are;
117649
823543
5764801
naǫ
[tex]r=\frac{343}{49}=7 \\ \\ a_5=16807 \times 7=117649 \\ a_6=117649 \times 7=823543 \\ a_7=823543 \times 7=5764801[/tex]