Question

Terry has invented a new way to extend lists of numbers. To 'terryfy' a list such as [1,8] he creates 2 lists [2,9] and [3,10], where each term is one more than the corresponding term in the previous list, and then joins the three lists together to give [1,8,2,9,3,10]. If he starts with a list containing one number [0' and repeatedly 'Terryfies' it he creates the list
[0,1,2,1,2,3,2,3,4,1,2,3,2,3,4,3,4,5,2,3,4...]

What is the 2012th number in this 'Terryfy' list?