#871 · Combinatorics · Counting

Signs with no adjacent negatives

Prove that the number of ways to arrange $p$ positive signs and $n$ negative signs in a row such that no two negative signs are adjacent is $(n p + 1)$ .

~5 minProof · checked by AIcombinationsarrangements

H. S. Hall & S. R. Knight, Higher Algebra (1891) · Ch. XI. Permutations and Combinations, Examples XI.a, No. 31

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