Thank you so much for the help Alan!! I didn't think of doing that before but I understand why that is helpful now.
If my work is correct, the sum of the coefficients of the terms in g(x) that have even degree is 21,556,128.5
g(1)=f(1)16=(−32+12+4)16=316=43,046,721
g(−1)=f(−1)16=(−32−12+4)16=216=65,536
g(1)+g(−1)2=43,046,721+65,5362=43,112,2572=21,556,128.5
Thanks again for helping me solve this!