Hint: add to your induction hypothesis.
prove that it is divisible by 3 for any integer
the steps i use are
1) plug in a number to see if its true 1+2 = 3 is divisible by 3= true
2). K=N plug it in
3) K+1 =N plug it in ---- this is where I'm confused i usually have numbers for example 1+3+4+5+.......(3n+2) = n(n+1)
I'm not sure if step 3 is right because that's what i do for my usual example with numbers