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Search: id:A071398
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| A071398 |
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Rounded total surface area of a regular icosahedron with edge length n. |
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+0
5
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| 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; listen)
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OFFSET
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0,2
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REFERENCES
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S. Selby, editor, CRC Basic Mathematical Tables, CRC Press, 1970, pp. 10-11.
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LINKS
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Eric Weisstein's World of Mathematics, Link to a section of The World of Mathematics
Eric Weisstein's World of Mathematics, Link to a section of The World of Mathematics
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FORMULA
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a(n) = round(5 * n^2 * sqrt(3))
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EXAMPLE
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a(4)=139 because round(5*4^2*sqrt(3))=round(80*1.73205...)=round(138.56...)=139.
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PROGRAM
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(PARI) for(n=0, 100, print1(round(5*n^2*sqrt(3)), ", "))
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CROSSREFS
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Cf. A070169 (tetrahedron), A033581 (cube), A071396 (octahedron), A071397 (dodecahedron), A071402 (volume of icosahedron).
Sequence in context: A085366 A033566 A022275 this_sequence A005898 A034957 A002418
Adjacent sequences: A071395 A071396 A071397 this_sequence A071399 A071400 A071401
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KEYWORD
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easy,nonn
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AUTHOR
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Rick L. Shepherd (rshepherd2(AT)hotmail.com), May 29 2002
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