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 A102771 Decimal expansion of area of a regular pentagon with unit edge length. 12
 1, 7, 2, 0, 4, 7, 7, 4, 0, 0, 5, 8, 8, 9, 6, 6, 9, 2, 2, 7, 5, 9, 0, 1, 1, 9, 7, 7, 3, 8, 8, 6, 0, 9, 5, 9, 9, 4, 0, 7, 3, 7, 4, 1, 7, 0, 0, 1, 0, 1, 9, 8, 3, 2, 9, 2, 0, 7, 0, 9, 4, 7, 0, 7, 0, 2, 3, 8, 6, 8, 9, 9, 2, 2, 0, 8, 9, 6, 6, 2, 3, 1, 3, 3, 2, 4, 4, 1, 2, 4, 1, 3, 8, 7, 5, 8, 7, 7, 4 (list; constant; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 LINKS G. C. Greubel, Table of n, a(n) for n = 1..10000 Eric Weisstein's World of Mathematics, Pentagon FORMULA Equals sqrt(25 + 10*sqrt(5)) / 4. Equals (3*phi+1)*sqrt(3-phi) with the golden section phi = (1 + sqrt(5))/2. - Wolfdieter Lang, Jan 25 2013 Equals 5/(4*tan(Pi/5)). - Michel Marcus, Mar 25 2015 Equals (5/4)*sqrt(phi^3/sqrt(5)). - G. C. Greubel, Jul 03 2017 EXAMPLE 1.720477400588966922759011977... MATHEMATICA RealDigits[(5/4)*Sqrt[GoldenRatio^3/Sqrt[5]], 10, 50][[1]] (* G. C. Greubel, Jul 03 2017 *) PROG (PARI) 5/(4*tan(Pi/5)) \\ Michel Marcus, Mar 25 2015 CROSSREFS Cf. Areas of other regular polygons: A120011, A104956, A178817, A090488, A256853, A178816, A256854, A178809. Sequence in context: A258753 A248363 A220674 * A232812 A245740 A318922 Adjacent sequences:  A102768 A102769 A102770 * A102772 A102773 A102774 KEYWORD nonn,cons AUTHOR Bryan Jacobs (bryanjj(AT)gmail.com), Feb 10 2005 EXTENSIONS Corrected the title. - Stanislav Sykora, Apr 12 2015 STATUS approved

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Last modified January 18 04:47 EST 2019. Contains 319269 sequences. (Running on oeis4.)