Sharp eye...........I didn't review the information, assumed it was accurate..............how about this............
555 Timer Astable Calculator Description
Time High (T1) 0.693 × (R1+R2) × C1 Seconds
Time Low (T2) 0.693 × R2 × C1 Seconds
Time Period (T) 0.693 × (R1+2×R2) × C1 Seconds
Frequency (F) 1.44 / (R1+2×R2) × C1 Hertz (Hz)