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Problem 581

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47-smooth triangular numbers

A number is p-smooth if it has no prime factors larger than p.
Let T be the sequence of triangular numbers, ie T($n$)=$n$($n$+1)/2.
Find the sum of all indices $n$ such that T($n$) is 47-smooth.

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47-光滑三角形数

如果一个数没有大于p的质因数，则称其为p-光滑数。
令T表示三角形数数列，也就是说T($n$)=$n$($n$+1)/2。
求出所有使得T($n$)为47-光滑的下标$n$的和。

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