A231981 - OEIS

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

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OFFSET

4,1

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)).

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

FORMULA

(180/Pi)^2.

EXAMPLE

3282.80635001174379478169460799517550050122429938078818259773...

MATHEMATICA

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

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.

Sequence in context: A113794 A086774 A153461 * A344577 A019666 A110938

Adjacent sequences: A231978 A231979 A231980 * A231982 A231983 A231984

KEYWORD

nonn,cons,easy

AUTHOR

Stanislav Sykora, Nov 16 2013

STATUS

approved