a(n) is the smallest positive integer k such that d(k) = d(k+n) = 2*n, where d(m) (A000005) is the number of positive divisors of m, or 0 if no such k exists.
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a(n) = ) is the smallest positive integer k such that d(k) = d(k+n) = 2n2*n, where d(m) (A000005) is the number of positive divisors of m, or 0 if no such k exists.