A217572 Decimal expansion of the conversion factor from radians to arcseconds.

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

Offset: 6

Author

R. J. Mathar, Oct 10 2012

Keywords

• cons
• nonn
• easy

Comments

From Peter Munn, Aug 21 2020 and Nov 11 2020: (Start)

Corresponds to a significant mark labeled with a (typographic) double prime symbol on slide rule calculating devices in the 20th century. The Pickworth reference explains its use for sines and tangents of small angles.

As tangents of small angles can be approximated by the angle itself, this value approximates the cotangent of an arcsecond, and so, to within 1 part in 10^11, the number of astronomical units in a parsec, prior to its redefinition in August 2015. (End)

Equals the number of astronomical units in a parsec, as defined in 2015. - Donghwi Park, Aug 08 2021

Examples

			206264.806247096355156473...
		

References

• C. N. Pickworth, The Slide Rule, 24th Ed., Pitman, London, 1945, pp. 76-78, Trigonometrical Applications.

Links

• Robert G. Wilson v, Table of n, a(n) for n = 6..1005
• Peter Munn, Aristo 89 Slide Rule.
• Wikipedia, Parsec.
• Wikipedia, Minute and second of arc.
• Index entries for transcendental numbers

Crossrefs

Related conversion factors: A155970 (arcseconds to radians), A072097 (radians to degrees), A337493 (radians to arcminutes).

Programs

Maple

evalf(180/Pi*3600) ;

Mathematica

RealDigits[(180/Pi) 3600, 10, 75][[1]] (* Bruno Berselli, Oct 10 2012 *)

Maxima

fpprec:77; ev(bfloat((180/%pi)*3600)); /* Bruno Berselli, Oct 10 2012 */

Formula

Equals 3600 * A072097.

Equals 1/A155970.