Let be positive integers such that

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Problem

Let n1<n2<n3<n4<n5n_1<n_2<n_3<n_4<n_5 be positive integers such that n1+n2+n3+n4+n5=20n_1+n_2+n_3+n_4+n_5=20. Find the number of distinct arrangements (n1,n2,n3,n4,n5)(n_1,n_2,n_3,n_4,n_5).

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