cp's OEIS Frontend

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

%I A217572 #71 Jan 12 2025 17:35:52
%S A217572 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,
%T A217572 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,
%U A217572 0,2,4,9,7,3,3
%N A217572 Decimal expansion of the conversion factor from radians to arcseconds.
%C A217572 From _Peter Munn_, Aug 21 2020 and Nov 11 2020: (Start)
%C A217572 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.
%C A217572 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)
%C A217572 Equals the number of astronomical units in a parsec, as defined in 2015. - _Donghwi Park_, Aug 08 2021
%D A217572 C. N. Pickworth, The Slide Rule, 24th Ed., Pitman, London, 1945, pp. 76-78, Trigonometrical Applications.
%H A217572 Robert G. Wilson v, <a href="/A217572/b217572.txt">Table of n, a(n) for n = 6..1005</a>
%H A217572 Peter Munn, <a href="/A337092/a337092.jpg">Aristo 89 Slide Rule</a>.
%H A217572 Wikipedia, <a href="http://en.wikipedia.org/wiki/Parsec">Parsec</a>.
%H A217572 Wikipedia, <a href="http://en.wikipedia.org/wiki/Minute_and_second_of_arc">Minute and second of arc</a>.
%H A217572 <a href="/index/Tra#transcendental">Index entries for transcendental numbers</a>
%F A217572 Equals 3600 * A072097.
%F A217572 Equals 1/A155970.
%e A217572 206264.806247096355156473...
%p A217572 evalf(180/Pi*3600) ;
%t A217572 RealDigits[(180/Pi) 3600, 10, 75][[1]] (* _Bruno Berselli_, Oct 10 2012 *)
%o A217572 (Maxima) fpprec:77; ev(bfloat((180/%pi)*3600)); /* _Bruno Berselli_, Oct 10 2012 */
%Y A217572 Related conversion factors: A155970 (arcseconds to radians), A072097 (radians to degrees), A337493 (radians to arcminutes).
%K A217572 cons,nonn,easy
%O A217572 6,1
%A A217572 _R. J. Mathar_, Oct 10 2012