

A179294


Decimal expansion of radius of inscribed sphere about a regular icosahedron with edge = 1.


25



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
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OFFSET

0,1


COMMENTS

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


LINKS

Table of n, a(n) for n=0..104.
"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: A158244 A226580 A182007 * A011474 A171536 A233822
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



