pascal代码，数学数列知识，直接贴码，不多说 program U34202; var i,a,b:longint; sum,k,c,w:int64; begin {assign(input,'1.txt');reset(input); assign(output,'2.txt');rewrite(output);} readln(a,b); k:=1; c:=b div 2; sum:=0; if a=1 then begin dec(sum);a:=2;end; for i:=1 to c do begin k:=k*(-1); if a>=2*i+1 then w:=a div i else w:=2; sum:=sum+k*i*((w+b div i)*(b div i-w+1) div 2); sum:=sum-k*((i-((a div i+1)*i-a))*(a div i)); sum:=sum-k*((i-(b-(b div i-1)*i)+i-1)*(b div i)); end; for i:=a to b do if (i-i div 2) mod 2<>0 then begin if (i div 2) mod 2=1 then in
