Γ ( − 3 / 2 ) = 4 π 3 ≈ 2.363 Γ ( − 1 / 2 ) = − 2 π ≈ − 3.545 Γ ( 1 / 2 ) = π ≈ 1.772 Γ ( 1 ) = 0 ! = 1 Γ ( 3 / 2 ) = π 2 ≈ 0.886 Γ ( 2 ) = 1 ! = 1 Γ ( 5 / 2 ) = 3 π 4 ≈ 1.329 Γ ( 3 ) = 2 ! = 2 Γ ( 7 / 2 ) = 15 π 8 ≈ 3.323 Γ ( 4 ) = 3 ! = 6 {\displaystyle {\begin{array}{lll}\Gamma (-3/2)&={\frac {4{\sqrt {\pi }}}{3}}&\approx 2.363\\\Gamma (-1/2)&=-2{\sqrt {\pi }}&\approx -3.545\\\Gamma (1/2)&={\sqrt {\pi }}&\approx 1.772\\\Gamma (1)&=0!&=1\\\Gamma (3/2)&={\frac {\sqrt {\pi }}{2}}&\approx 0.886\\\Gamma (2)&=1!&=1\\\Gamma (5/2)&={\frac {3{\sqrt {\pi }}}{4}}&\approx 1.329\\\Gamma (3)&=2!&=2\\\Gamma (7/2)&={\frac {15{\sqrt {\pi }}}{8}}&\approx 3.323\\\Gamma (4)&=3!&=6\\\end{array}}}