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The solution of a recursive sequence arising from a combinatorial problem in botanical epidemiology. (English) Zbl 1274.92048
Summary: One of the central problems in botanical epidemiology is whether disease spreads within crops in a regular pattern or follows a random process. In this study, we consider a row of $$n$$ plants in which $$m$$ are infected. We then develop a rigorous mathematical approach to investigate the total number of ways to obtain $$k$$ isolated individuals among $$m$$ infected plants. We give a recurrence relation in three parameters that describes the problem, then we find a closed-form solution, and give two different approaches to tackle the proof. Finally, we find interesting formulae for the expectation and variance of the random variable that represents the number of infected and isolated plants.

##### MSC:
 92D30 Epidemiology 65Q30 Numerical aspects of recurrence relations 05A05 Permutations, words, matrices 05A15 Exact enumeration problems, generating functions
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##### References:
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