cp's OEIS Frontend

Radius of a circle with area 1.

Expectation of the maximum of a size 2 sample from a normal (0,1) distribution. - Jean-François Alcover, Jun 05 2014

More generally, the ratio (surface)/(volume)^(2/3), characteristic of the shape of a bounded 3D body, which is invariant under linear scaling and known as the surface index. Its common value for all spheres is the smallest possible among all closed 3D bodies (for a cube, for example, it is exactly 6.0).

Radius of a sphere with surface area 1.

According to Fouad (2004), to simulate the distance of a sound source under free field conditions, one can multiply "the waveform directly by a gain factor that is the square root of the intensity," which can be computed with the formula D = sqrt(1/(4 * Pi * d^2)) = 1/(3.55 * d), where d is the distance between the sound source and the listener and 3.55 is approximately 10(sqrt(Pi)/5) (A019707) (equation 15 in the chapter), though "in practice we usually drop the constant multiplier" (4 * Pi). If the distance is one unit, then D works out to this number. - Alonso del Arte, Jun 10 2012