for _ in range(int(input())):
    n=int(input())
    a=[int(i) for i in input().split()]
    max_bit=[0]*32
    min_bit=[10**9]*32
    for i in range(n):
        b=(len(bin(a[i])))-2
        max_bit[b]=max(max_bit[b],a[i])
        min_bit[b]=min(min_bit[b],a[i])
    #print(max_bit)
    #print(min_bit)
    ans=-1
    for i in range(1,32):
        for j in range(1,32):
            X=max_bit[i]
            Y=min_bit[j]
            if X==0 or Y==10**9:
                continue
            else:
                d=(X*(2**j - 1))-(Y*(2**i - 1))
                ans=max(ans,d)
    print(ans)

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MwoxCjEKMgo1IDkKNwoxIDIgNCA4IDE2IDY0IDEyOA==

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1
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2
5 9
7
1 2 4 8 16 64 128