%I A137914
%S A137914 1,2,3,0,9,5,9,4,1,7,3,4,0,7,7,4,6,8,2,1,3,4,9,2,9,1,7,8,2,4,7,9,8,7,3,
%T A137914 7,5,7,1,0,3,4,0,0,0,9,3,5,5,0,9,4,8,3,9,0,5,5,5,4,8,3,3,3,6,6,3,9,9,2,
%U A137914 3,1,4,4,7,8,2,5,6,0,8,7,8,5,3,2,5,1,6,2,0,1,7,0,8,6,0,9,2,1,1,3,8,9,4
%N A137914 Decimal expansion of arccos(1/3).
%C A137914 Dihedral angle in radians of regular tetrahedron.
%C A137914 Arccos(1/3) is the central angle of a cube, made by the center and two 
               neighboring vertices. [From Clark Kimberling (ck6(AT)evansville.edu), 
               Feb 10 2009]
%H A137914 Jackson, Frank and Weisstein, Eric W., <a href="http://mathworld.wolfram.com/
               Tetrahedron.html">Tetrahedron</a>
%H A137914 Weisstein, Eric W., <a href="http://mathworld.wolfram.com/DihedralAngle.html">
               Dihedral Angle</a>
%F A137914 arccos(1/3) = arctan(2*sqrt(2)) = 2*arcsin(sqrt(3)/3) = arcsin(2*sqrt(2)/
               3).
%e A137914 1.2309594173407746821349291782479873757103400093550948390555483336639923144...
%o A137914 (PARI) acos(1/3)
%Y A137914 Cf. A137915 (same in degrees).
%Y A137914 Sequence in context: A020823 A021437 A074760 this_sequence A098989 A012399 
               A012403
%Y A137914 Adjacent sequences: A137911 A137912 A137913 this_sequence A137915 A137916 
               A137917
%K A137914 cons,nonn
%O A137914 1,2
%A A137914 Rick L. Shepherd (rshepherd2(AT)hotmail.com), Feb 22 2008