Something fishy in the series

the serie is :

$1 \times 2^2=4, 2 \times 3^2=18,3 \times 4^2=48,4 \times 5^2=100,5 \times 6^2=180...$

I had a different approach to this..... well the given series is 4,18,48,100,...so now remove difference between the (n+1)th term and the nth term so the new series is 14,30,52,....again remove difference similarly to the first one.....so the new series is 16,22......once again you do this you get a single number i.e 6.....continuing the series which will be 6,12,18.....so for the previous series which is 16,22...next term will be 22+6=28 now add 28 to the previous series's last no. i.e 52+28=80 and finally add 80 to 100 to get the term in the series asked....which will be 180....(the approach is to breakdown the series by difference method)