Boy, that escalated quickly (Fixed)
Let be a positive integer satisfying . Compute .
The answer is 3912873140.
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1 solution
Obviously n = 2 . So the summation becomes x = 1 ∑ 1 0 2 x ( x ! + x 2 ) , which is 4 + 2 4 + 1 2 0 + 6 4 0 + 4 6 4 0 + 4 8 3 8 4 + 6 5 1 3 9 2 + 1 0 3 3 8 3 0 4 + 1 8 5 8 3 6 0 3 2 + 3 7 1 5 9 9 3 6 0 0 = 3 9 1 2 8 7 3 1 4 0 .