CODYHMV3SKPFHIODHTCDCMKC7FDRQAQZISC2YKI2YUJXPG4UEOAQC // SumSquare returns the total number of grains to n-th square.// SumSquare(64) == Total()func SumSquare(n int) (uint64, error) {if n < 1 || n > 64 {return 0, fmt.Errorf("input must be positive and <= 64, got: %q", n)}return 1<<n - 1, nil}