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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 (list; constant; graph; refs; listen; history; text; internal format)
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]^2-1==0, {t, 54}, WorkingPrecision-> 120]][[1]] (* Harvey P. Dale, May 02 2014 *)

CROSSREFS

Cf. A195696 (in radians).

Sequence in context: A246724 A199276 A021870 * A177161 A154776 A188932

Adjacent sequences:  A210971 A210972 A210973 * A210975 A210976 A210977

KEYWORD

nonn,cons

AUTHOR

Omar E. Pol, Jul 17 2012

STATUS

approved

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Last modified July 20 14:50 EDT 2017. Contains 289625 sequences.