利用者:Merliborn/sandbox/sfrac

{{Sfrac|n(n+1)|2}}

n(n+1)/2

{{Math|{{Sfrac|n(n+1)|2}}}}

n(n+1)/2

:{{Math|{{Sfrac|n(n+1)|2}}}}

n(n+1)/2

{{Math|''S'' = {{Sfrac|n(n+1)|2}}}}

S = n(n+1)/2

• n(n+1)/2