A249521 Decimal expansion of 4/sqrt(Pi), the average distance between two random Gaussian points in three dimensions.

2, 2, 5, 6, 7, 5, 8, 3, 3, 4, 1, 9, 1, 0, 2, 5, 1, 4, 7, 7, 9, 2, 3, 1, 7, 8, 0, 6, 2, 4, 3, 0, 9, 0, 3, 4, 3, 3, 7, 6, 2, 0, 2, 5, 1, 7, 3, 1, 5, 9, 9, 5, 4, 2, 7, 3, 7, 6, 3, 4, 2, 8, 8, 6, 8, 4, 2, 5, 6, 9, 8, 7, 3, 7, 6, 5, 9, 7, 3, 6, 5, 7, 9, 4, 6, 9, 7, 4, 6, 4, 0, 8, 0, 8, 4, 2, 9, 4, 5, 3, 7, 7, 2

Offset: 1

Author

Jean-François Alcover, Oct 31 2014

Keywords

• nonn
• cons
• easy

Comments

Coordinates are independent normally distributed random variables with mean 0 and variance 1.

Examples

			2.25675833419102514779231780624309034337620251731...
		

Links

• G. C. Greubel, Table of n, a(n) for n = 1..5000
• Steven R. Finch, Random Triangles, Jan 21 2010. [Cached copy, with permission of the author]
• Index entries for transcendental numbers.

Crossrefs

Cf. A002161 (the analog constant in two dimensions), A087197, A190732 (the analog constant in one dimension).

Programs

Mathematica

RealDigits[4/Sqrt[Pi], 10, 103] // First

PARI

4/sqrt(Pi) \\ G. C. Greubel, Jan 09 2017

Formula

Equals Sum_{k>=0} k!/(k+3/2)!. - Amiram Eldar, Jun 19 2023