26088

WHEN I first had a go at this it got a bit comfusing then I realized that if you times the second number by three and I tested it on a really big number like 598216+598217+598218 is 1794651 and 598217x3 is 1794651. I didn't realize the formula because it again got a bit comfusing. Theres also another pattern when you've done it is that you add three every time eg six add three is nine and nine add three is twelve and three add four add five is twelve.