RT，求 ∑i=n1∏j=1i(2j2−j)\sum_{i = n}^{1}\prod_{j=1}^{i}(2j^2-j)∑i=n1∏j=1i(2j2−j) 及 ∑i=n1∏j=1i(2j2+j)\sum_{i = n}^{1}\prod_{j=1}^{i}(2j^2+j)∑i=n1∏j=1i(2j2+j)
