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A179294 Decimal expansion of radius of inscribed sphere about a regular icosahedron with edge = 1. 26
7, 5, 5, 7, 6, 1, 3, 1, 4, 0, 7, 6, 1, 7, 0, 7, 3, 0, 4, 8, 0, 1, 3, 3, 7, 0, 2, 0, 2, 5, 0, 0, 1, 3, 9, 2, 6, 3, 8, 4, 4, 4, 7, 8, 8, 8, 9, 3, 5, 6, 1, 0, 5, 9, 2, 2, 9, 5, 8, 2, 8, 9, 2, 0, 3, 9, 1, 0, 6, 8, 4, 5, 2, 2, 1, 9, 4, 8, 2, 6, 2, 0, 6, 3, 5, 6, 0, 4, 9, 4, 7, 6, 0, 8, 6, 8, 2, 7, 0, 4, 1, 1, 9, 3, 1 (list; constant; graph; refs; listen; history; text; internal format)
OFFSET

0,1

COMMENTS

Icosahedron: A three dimensional figure with 20 equilateral triangle faces, 12 vertices, and 30 edges.

LINKS

Ivan Panchenko, Table of n, a(n) for n = 0..1000

Dr. Math, Icosahedron

Wikipedia, Icosahedron

MathWorld, Icosahedron

FORMULA

Sqrt(42 + 18*sqrt(5))/12

EXAMPLE

0.75576131407617073048013370202500139263844478889356105922958289203910...

MATHEMATICA

a=1; RealDigits[N[(Sqrt[42+18Sqrt[5]]/12)*a, 175]]

CROSSREFS

Cf. A010527, A102208, A179290, A179292.

Cf. Platonic solids inradii: A020781 (tetrahedron), A020763 (octahedron), A237603 (dodecahedron).

Sequence in context: A226580 A182007 A247320 * A259679 A247876 A011474

Adjacent sequences:  A179291 A179292 A179293 * A179295 A179296 A179297

KEYWORD

nonn,cons,easy

AUTHOR

Vladimir Joseph Stephan Orlovsky, Jul 09 2010

EXTENSIONS

Partially rewritten by Charles R Greathouse IV, Feb 03 2011

STATUS

approved

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Last modified December 4 21:09 EST 2016. Contains 278755 sequences.