The On-Line Encyclopedia of Integer Sequences (OEIS)

Revision History for A179292 (Bold, blue-underlined text is an addition; faded, red-underlined text is a ~~deletion~~.)
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A179292

Decimal expansion of radius of inscribed sphere of an icosahedron with radius of circumscribed sphere = 1.
(history; published version)

#12 by Charles R Greathouse IV at Sun Feb 16 08:33:12 EST 2025

LINKS

MathWorld, <a href="httphttps://mathworld.wolfram.com/Icosahedron.html">Icosahedron</a>

Discussion

Sun Feb 16

08:33

OEIS Server: https://oeis.org/edit/global/3014

#11 by Charles R Greathouse IV at Mon Sep 02 10:04:02 EDT 2024

STATUS

editing

approved

#10 by Charles R Greathouse IV at Mon Sep 02 10:03:59 EDT 2024

LINKS

<a href="/index/Al#algebraic_04">Index entries for algebraic numbers, degree 4</a>.

PROG

(PARI) polrootsreal(45*x^4-30*x^2+1)[4] \\ Charles R Greathouse IV, Sep 02 2024

(PARI) sqrt(6/sqrt(5)+3)/3 \\ Charles R Greathouse IV, Sep 02 2024

STATUS

approved

editing

#9 by Jon E. Schoenfield at Wed Jan 19 21:27:11 EST 2022

STATUS

proposed

approved

#8 by Jon E. Schoenfield at Wed Jan 19 21:20:08 EST 2022

STATUS

editing

proposed

#7 by Jon E. Schoenfield at Wed Jan 19 21:20:06 EST 2022

COMMENTS

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

FORMULA

Sqrt(75 + 30*sqrt(5))/15.

STATUS

approved

editing

#6 by Russ Cox at Sat Mar 31 12:38:37 EDT 2012

AUTHOR

_Vladimir Joseph Stephan Orlovsky (4vladimir(AT)gmail.com), _, Jul 09 2010

Discussion

Sat Mar 31

12:38

OEIS Server: https://oeis.org/edit/global/876

#5 by Russ Cox at Fri Mar 30 17:40:25 EDT 2012

EXTENSIONS

Offset corrected, keyword:cons added by _R. J. Mathar (mathar(AT)strw.leidenuniv.nl), _, Jul 11 2010

Discussion

Fri Mar 30

17:40

OEIS Server: https://oeis.org/edit/global/190

#4 by Charles R Greathouse IV at Thu Feb 03 09:49:52 EST 2011

STATUS

proposed

approved

#3 by Charles R Greathouse IV at Thu Feb 03 09:49:47 EST 2011

COMMENTS

0.79465447229176612295553092832759404202659058830926480175495577500843864497173711679302729948487087137852824227348554432360.. Icosahedron: A three dimensional figure with 20 equilateral triangle faces, 12 vertices, and 30 edges.

LINKS

Mathforum, <a href="http://mathforum.org/dr.math/faq/formulas/faq.polyhedron.html#icosahedron">Icosahedron</a> Mathforum

Wikipedia, <a href="http://en.wikipedia.org/wiki/Icosahedron">Icosahedron</a>, Wikipedia

MathWorld, <a href="http://mathworld.wolfram.com/Icosahedron.html">Icosahedron</a> Mathworld

<a href="http://www.wolframalpha.com/input/?i=Icosahedron">Icosahedron</a> Wolfram alpha

FORMULA

Sqrt(75 + 30*sqrt(5))/15

EXAMPLE

0.794654472291766122955530928327594042026590588309264801754955775008438...

CROSSREFS

Cf. A010527, A102208, A179290.

KEYWORD

nonn,cons,easy

STATUS

approved

proposed