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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 Vincenzo Librandi, Table of n, a(n) for n = 0..10000 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 Adjacent sequences:  A071395 A071396 A071397 * A071399 A071400 A071401 KEYWORD easy,nonn AUTHOR Rick L. Shepherd, May 29 2002 STATUS approved

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Last modified October 19 13:01 EDT 2019. Contains 328222 sequences. (Running on oeis4.)