【２】∫(0,∞)Πsin(kx)/(kx)dx=?

　　∫(0,∞)sinc(x)=π/2

　　∫(0,∞)sinc(x)sinc(2x)dx=π/4

　　∫(0,∞)sinc(x)sinc(2x)sinc(4x)dx=π/8

　　∫(0,∞)sinc(x)sinc(2x)sinc(4x)sinc(8x)dx=π/16

　　∫(0,∞)sinc(x)=π/2

　　∫(0,∞)sinc(x)sinc(3x)dx=π/6

　　∫(0,∞)sinc(x)sinc(3x)sinc(9x)dx=π/18

　　∫(0,∞)sinc(x)sinc(3x)sinc(9x)sinc(27x)dx=π/54

　置換積分により

　　∫(0,∞)Πsin(x*n^i)/(x*n^i)dx=1/n^k∫(0,∞)sin(x)/(x)dx

すなわち，本質的に同じ積分となる．

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