Working with Binary numbers BASE(..., 2, 7) and bit operations BITXOR, BITAND

m_tarlerYes, having a repeatable random function can come in handy, I've quite often divided by 2^32 to get a non-volatile RAND alternative

PeterBartholomew1 Indeed, another possible candidate might be a 'combinations' function,

=combinations({"a";"b";"c";"d"},2)

which would return {"a","b";"a","c";"b","c";"a","d";"b","d";"c","d"}. I had been thinking about this off and on for a while but like SergeiBaklan couldn't see any reasonable route. I revisited again in light of the bisection method you provided recently based on a recursion over an array version of,

COMBIN(n,k) = COMBIN(n-1,k-1) + COMBIN(n-1,k)

For example with the following lambda definition =combinations(sequence(20),10) returns COMBIN(20,10)*10=1847560 elements.

combinations
=LAMBDA(arr, k,
    IF(
        k <= ROWS(arr),
        IF(
            k = 1,
            arr,
            DROP(
                VSTACK(
                    combinations(DROP(arr, -1), k),
                    EXPAND(combinations(DROP(arr, -1), k - 1), , k, @TAKE(arr, -1))
                ),
                k = ROWS(arr)
            )
        )
    )
)