Calculating and Outputting Pascal's Triangle with only Indices
This is SUPER bulky for what you actually need to be doing. I did this same project about a year ago in python3. You're thinking too hard about something that's a lot more simple than it looks.

while True:
  def num():
    n=input("Type however many rows you want (or 'info' for info about Pascal’s Triangle): ") 
  if n=="quit":
    exit()
  if n.isnumeric():
    n = int(n)
    if n&gt;1000:
      print("That's too many. Try again.")
      return
    else:
      a=[]
      for i in range(n):
        a.append([])
        a[i].append(1)
        for j in range(1,i):
          a[i].append(a[i-1][j-1]+a[i-1][j])
      if(n!=0):
        a[i].append(1)
        for i in range(n):
        print("   "*(n-i),end=" ",sep=" ")
        for j in range(0,i+1):
          print('{0:6}'.format(a[i][j]),end=" ",sep=" ")
        print()
  else:
    return
  num()


The indentation may be wrong (copy and paste is challenging) but it is a lot shorter and more efficient than all the checks you're doing.
Hopefully this helps!