Challenge - Print the following trinle

Question

1
2 6
3 7 10
4 8 11 13
5 9 12 14 15

Answer 1

thats a duplicate question my friend , already asked many times ... if i get link ,i'll post ... wait ... i'll make later if get time
//bookmarked
//can be done in 2 loops

Answer 2

https://code.sololearn.com/ccKaWgzH9DPc/#c