what is the rule for this sequence 3,5,15,65,315

Question

The sequence rule

Answer 1

5*3-10=5; 5*5-10=15; 5*15-10=65; 5*65-10=315; 5*315-10=1565.

a[n+1]=5a[n]-10 is the general recursive formula, where a1=3.

The general formula is f(n)=3*5^n-5((5^n)-1)/2, n>=0.

This can be written: f(n)=½((5^n)+5).

Comments

Yes, you probably will need to! You multiply the previous term by 5 and subtract 10 to get the next term in the series. The series starts with 3, so 5 times 3 less 10 is 5, then 5 times 5 less 10 is 15,and so on.

Answer 2

yeet, i dunno