#Jelly, 9 bytes
Jelly, 9 bytes
⁴L×3
ẋ¢ḣ¢
⁴L×3 Define nilad as ¢:
L length of
⁴ second argument
×3 tripled
ẋ¢ḣ¢ Main chain:
the first argument (implicit)
ẋ repeated
¢ ¢ many times
ḣ¢ then get the first ¢ characters of it.