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A071398 Rounded total surface area of a regular icosahedron with edge length n. 5
0, 9, 35, 78, 139, 217, 312, 424, 554, 701, 866, 1048, 1247, 1464, 1697, 1949, 2217, 2503, 2806, 3126, 3464, 3819, 4192, 4581, 4988, 5413, 5854, 6313, 6790, 7283, 7794, 8323, 8868, 9431, 10011, 10609, 11224, 11856, 12505, 13172, 13856, 14558, 15277 (list; graph; refs; listen; history; text; internal format)
OFFSET
0,2
REFERENCES
S. Selby, editor, CRC Basic Mathematical Tables, CRC Press, 1970, pp. 10-11.
LINKS
Eric Weisstein's World of Mathematics, Icosahedron
Eric Weisstein's World of Mathematics, Platonic Solid
FORMULA
a(n) = round(5 * n^2 * sqrt(3)).
EXAMPLE
a(4)=139 because round(5*4^2*sqrt(3)) = round(80*1.73205...) = round(138.56...) = 139.
MATHEMATICA
With[{c=5Sqrt[3]}, Round[c Range[0, 50]^2]] (* Harvey P. Dale, May 20 2011 *)
PROG
(PARI) for(n=0, 100, print1(round(5*n^2*sqrt(3)), ", "))
(Magma) [Round(5 * n^2 * Sqrt(3)): n in [0..50]]; // Vincenzo Librandi, May 21 2011
CROSSREFS
Cf. A070169 (tetrahedron), A033581 (cube), A071396 (octahedron), A071397 (dodecahedron), A071402 (volume of icosahedron).
Sequence in context: A033566 A226755 A022275 * A212099 A212100 A005898
KEYWORD
easy,nonn
AUTHOR
Rick L. Shepherd, May 29 2002
STATUS
approved

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Last modified July 14 22:52 EDT 2024. Contains 374323 sequences. (Running on oeis4.)