What are prime numbers?

Prime numbers are positive integers that have only 2 factors: Itself, and 1.

For example, 13 is a prime number because it has only 2 factors that are: 1 and 13.

1 is NOT a prime number as it only has 1 factor which is 1.

hello from mrbilldoesmath!

answer:

a(n) - a(n-1) -3

discussion:

this ones a bit interesting. given a(n) = 5 - 3n consider this:

a(n-1) = 5 - 3(n-1)

          = (5 - 3n) + 3             => but a(n) = 5 - 3n, the first term

          = a(n)   + 3                 => subtract 3 from both sides

a(n-1) -3 = a(n)  

or

a(n) - a(n-1) -3

you,

mrb