R = 1/(1+1/(1+2/(1+3/(1+4/(…))))）=（√e）∫[1,∞］ｅ^（-xx/2）dx = √(eπ/2）・erfc（1/√2）= 0.6556795424188

S = Σ[k=1,∞］１/(2k-1）!! =（√e）∫[0,1］ｅ^（-xx/2）dx = √(eπ/2）・erf（1/√2）= 1.4106861346424

辺々たすと

R + S =（√e）∫[0,∞］ｅ^（-xx/2）dx = √(eπ/2）= 2.0663656770612