View Compilation Error

0_0_32864152_15632.cpp:1:1: error: expected unqualified-id before '<' token
 <span class="shx-hilit" title="Count : 26" style="line-height:1.1em;"></span>n*(n+1)*(2*n+1)*((3*n*n+3*n-1)/30<span class="sh-symbol" style="line-height:1.1em;color:rgb(255,0,0);"></span>//https://blog.csdn.net/Dacc123/article/details/51315063
 ^