## 47-smooth triangular numbers

### Problem 581

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.

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.