A231981 Decimal expansion of one steradian (sr) expressed in square degrees.

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

Offset: 4

Author

Stanislav Sykora, Nov 16 2013

Keywords

• nonn
• cons
• easy

Comments

This is the conversion ratio between two solid-angle measures: steradians and square degrees, applicable to integration infinitesimals. The square degree must not be confused with a finite spherical square having one degree side (see A231983, A231984, A231985), just as one steradian must not be confused with the solid angle covered by a spherical square with a side arc-length of one radian (see A231986, A231987).

Equals also full solid angle expressed in degrees, divided by 4*Pi (i.e., A125560/(4*Pi)).

Examples

			3282.80635001174379478169460799517550050122429938078818259773...
		

References

• G. V. Brummelen, Heavenly Mathematics: The Forgotten Art of Spherical Trigonometry, Princeton University Press, 2012, ISBN 978-0691148922.

Links

• Stanislav Sykora, Table of n, a(n) for n = 4..2000
• Wikipedia, Steradian
• Wikipedia, Square degree
• Index entries for transcendental numbers

Crossrefs

Cf. A000796 (Pi), A125560 (full solid angle), A072097 (rad/deg), A019685 (deg/rad), A231982 (inverse, deg^2/sr), A231983 (square with 1 deg side, in sr), A231984 (square with 1 deg side, in square degrees), A231985, A231986 (square with 1 rad side, in sr), A231987.

Programs

Mathematica

RealDigits[(180/Pi)^2,10,120][[1]] (* Harvey P. Dale, Nov 23 2019 *)

Formula

(180/Pi)^2.