aan(n-1) rings a bell with all these new posts.
Supposedly this type of integer is easy to spot.
Although we haven't discovered the identification process.
Lol.
product of triangles and squares, i think.
Best idea I can think of is to find the next largest perfect square, which should be (aann)
Subtract the difference of (aann) and aan(n-1)
For c145 it's 625-500 = 125
Then, aan(n-1) / 125 = 500 / 125 = 4 = (n-1)