[已经解决，请删除]求助读懂程序

qibbxxt

本人遇到一段Mathematica的代码，因为没有接触，看不明白，请高人指点


a[1] = 0; a[n_] := With[{fi = Select[ FactorInteger[n], Mod[#[[1]], 4] == 1 & ][[All, 2]]}, (Times @@ (2*fi+1)-1)/2]; Table[a[n], {n, 1, 99}] (* Jean-François Alcover, Feb 06 2012, after first formula )