>>298
{1+1/(2・3)}{1+1/(3・4)}・・・{1+1/[(n+1)・(n+2)]}
<e^{1/(2・3)+1/(3・4)+・・・+1/[(n+1)・(n+2)]}
= e^{(1/2)-(1/3)+(1/3)-(1/4)+・・・+1/(n+1)-1/(n+2)}
= e^{(1/2)-1/(n+2)}
<e^(1/2)