

A210974


Decimal expansion of the angle (in degrees) between an edge and (the normal of) a face of the regular tetrahedron.


2



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

2,1


COMMENTS

Also known as "magic angle", the angle t such that 3*(cos t)^2  1 = 0.
See more comments in A195696.  Stanislav Sykora, Nov 14 2013


LINKS

Table of n, a(n) for n=2..76.
Wikipedia, Tetrahedron
Wikipedia, Magic angle


FORMULA

A195696 times 180 divided through Pi, see A072097.


EXAMPLE

54.7356103172453... degrees.


MATHEMATICA

RealDigits[t/.FindRoot[3Cos[t Degree]^21==0, {t, 54}, WorkingPrecision> 120]][[1]] (* Harvey P. Dale, May 02 2014 *)


PROG

(PARI) acos(sqrt(1/3))*180/Pi \\ Charles R Greathouse IV, Nov 05 2017


CROSSREFS

Cf. A195696 (in radians).
Sequence in context: A199276 A293380 A021870 * A177161 A154776 A188932
Adjacent sequences: A210971 A210972 A210973 * A210975 A210976 A210977


KEYWORD

nonn,cons


AUTHOR

Omar E. Pol, Jul 17 2012


STATUS

approved



