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I test this law with a 7-bits primitive polynomial LFSR. and the run property could be found according to output. Is there any theoretical to prove m-sequence property, I could just find some conclusion on some literature.

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General property for a primitive LFSR:

Each nonzero bitstring of length $k$ where $k\leq m,$ occurs $2^{m-k+1}$ times while the all zero bitstring occurs $2^{m-k+1}-1$ times, in a single period of the LFSR. The run of $k$ 1’s is just one of those nonzero bitstrings.

For $k>m,$ some patterns never occur. The ones that do occur are exactly those patterns that satisfy parity checks which correspond to polynomial multiples of the generating polynomial.

Example: For the generating polynomial $x^4+x+1,$ the generating parity check is $$s_{t-4}\oplus s_{t-1}\oplus s_t=0.$$ Since $$(x+1)(x^4+x+1)=x^5+x^4+x^2+1,$$ the only $5-$tuples that occur at the output of this generator are those satisfying $$ s_{t-5}\oplus s_{t-4} \oplus s_{t-2}\oplus s_t=0.$$

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