How many enhances does it take to make an ST?

Starting from a 119 ST (assumption: 104 + 3 50%) for 74 total
11x3 enhancements -> 152
13x4 enhancements -> 204
10x5 enhancements -> 254
8x6 enhancements -> 302
7x7 enhancements -> 351
7x8 enhancements -> 407
5x9 enhancements -> 452
5x10 enhancements -> 502
5x11 enhancements -> 557
3x12 enhancements -> 593 atk
If I start it at 120 atk, it ends up 600 atk. So there's some glitch in there.