The coefficient of $x^{50}$ in
\[(1 + x)^{1000} + 2x (1 + x)^{999} + 3x^2 (1 + x)^{998} + \dots + 1001x^{1000}\]can be expressed in the form $\binom{n}{k}.$  Find the smallest possible value of $n + k.$
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The coefficient of $x^{50}$ in
\[(1 + x)^{1000} + 2x (1 + x)^{999} + 3x^2 (1 + x)^{998} + \dots + 1001x^{1000}\]can be expressed in the form $\binom{n}{k}.$  Find the smallest possible value of $n + k.$
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The coefficient of $x^{50}$ in
\[(1 + x)^{1000} + 2x (1 + x)^{999} + 3x^2 (1 + x)^{998} + \dots + 1001x^{1000}\]can be expressed in the form $\binom{n}{k}.$  Find the smallest possible value of $n + k.$
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