This site is supported by donations to The OEIS Foundation.

Thanks to everyone who made a donation during our annual appeal!
To see the list of donors, or make a donation, see the OEIS Foundation home page.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A231984 Decimal expansion of the solid angle (in deg^2) of a spherical square having sides of one degree. 6
 9, 9, 9, 9, 7, 4, 6, 1, 6, 4, 3, 9, 2, 7, 8, 6, 5, 4, 3, 2, 1, 9, 8, 5, 0, 9, 4, 7, 8, 4, 9, 6, 8, 2, 2, 5, 5, 1, 7, 9, 5, 9, 1, 5, 2, 4, 1, 8, 5, 7, 6, 4, 5, 2, 7, 4, 0, 6, 4, 6, 7, 2, 8, 4, 2, 8, 1, 4, 8, 7, 7, 7, 6, 0, 7, 1, 7, 3, 3, 6, 5, 8, 1, 8, 1, 5, 1, 7, 6, 0, 5, 8, 9, 6, 7, 7, 1, 4, 7, 6, 7, 1, 4, 5, 7 (list; constant; graph; refs; listen; history; text; internal format)
 OFFSET 0,1 COMMENTS See the comments to A231983 which will make it clear why on a sphere the solid angle of a square with one degree arc-length side is not exactly one deg^2. The correct value, shown here, is A231983*A231981. 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 = 0..2000 Wikipedia, Solid angle, Section 3.3 (Pyramid) Wikipedia, Square degree Wikipedia, Steradian FORMULA 4*arcsin(sin(R/2)sin(S/2))*(180/Pi)^2, where R = S = Pi/180. EXAMPLE 0.9999746164392786543219850947849682255179591524185764527406467... MATHEMATICA RealDigits[4*ArcSin[Sin[Pi/360]^2](180/Pi)^2, 10, 120][[1]] (* Harvey P. Dale, Aug 20 2017 *) PROG (PARI) default(realprecision, 120); 4*asin(sin(Pi/360)^2)*(180/Pi)^2 \\ Rick L. Shepherd, Jan 28 2014 CROSSREFS Cf. A000796 (Pi), A072097 (rad/deg), A019685 (deg/rad), A231981 (sr/deg^2), A231982 (deg^2/sr), A231983 (this constant in sr), A231987 (for square with 1 rad side), A231985, A231986. Sequence in context: A111691 A093409 A111692 * A288238 A100547 A259150 Adjacent sequences:  A231981 A231982 A231983 * A231985 A231986 A231987 KEYWORD nonn,cons,easy AUTHOR Stanislav Sykora, Nov 17 2013 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified January 16 01:15 EST 2019. Contains 319184 sequences. (Running on oeis4.)