1 1
2 3 2
4 5 6 3
7 8 9 10 4
11 12 13 14 15 5
.
n n+1 .k
n=k(k-1)/2+1;;
2013>=k(k-1)/2+1; k=63 63*62/2+1=1954,2013-1954+1=60
63行60