From a similar thread where I was given a link (with formula and 8 size
samples), I ran some numbers on star sizes and longevity and was surprized
to find that, while the math works fine for the 5 smallest stars, it
diverges dramatically for the three largest samples. Is the formula only
applicable for smaller stars? Does some other variable play a part? Or
what? (I assume the table is correct and not the calculated values.)

The left two columns and the formula was from:
http://www.astronomynotes.com/evolutn/s2.htm , while the right column was
calculated in Excel.

1/(SM/1)(4-1) × 10^10 years
star mass
(solar Calculated
masses) time (years) (years)
0.1 1000's billions 10^13
1 10 billion 10^10
1.5 3 billion 2,962,962,963
3 370 million 370,370,370
5 80 million 80,000,000
10 32 million 10,000,000 (Diverges)
30 11 million 370,370 ( -"-)
60 3 million 46,296 ( -"-)

Why the divergence?
TIA. Regards, Brett (still not homework) Aubrey.