V, 13 bytes (non-competing)
17é0òÄlxx>òr*
This is non-competing because V is newer than the challenge, but it's fun to beat the accepted answer by a huge margin. :D
Explanation:
17é0 " Insert 17 '0's
ò ò " Recursively:
Ä " Copy this line upwards
l " Move one char to the right
xx " Delete two characters
> " Indent this line
r* " Replace the last character with an asterisk
DJMcMayhem
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