Trendline equation

Hi, I am attempting to find an equation to fit a curve that I have plotted in Excel. I use the trendline function and get an equation but when i place that formula in excel and with the values they are different. I have attached the spreadsheet to show you. The yellow columns are my original data. The blue columns are the numbers i get from the trendline equation. My R-squared value is 1.0 for both too. Any help is beneficial thanks.