sgamma(1)=0.999999989064903 	 0!=1
sgamma(2)=0.999999989064903 	 1!=1
sgamma(3)=1.99999997812981 	 2!=2
sgamma(4)=5.99999993438942 	 3!=6
sgamma(5)=23.9999997375577 	 4!=24
sgamma(6)=119.999998687788 	 5!=120
sgamma(7)=719.99999212673 	 6!=720
sgamma(8)=5039.99994488711 	 7!=5040
sgamma(9)=40319.9995590969 	 8!=40320