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 A307681 Difference between the number of diagonals and the number of sides for a convex n-gon. 0
 -3, -2, 0, 3, 7, 12, 18, 25, 33, 42, 52, 63, 75, 88, 102, 117, 133, 150, 168, 187, 207, 228, 250, 273, 297, 322, 348, 375, 403, 432, 462, 493, 525, 558, 592, 627, 663, 700, 738, 777, 817, 858, 900, 943, 987, 1032, 1078, 1125, 1173, 1222, 1272, 1323, 1375, 1428, 1482, 1537, 1593, 1650, 1708, 1767, 1827, 1888, 1950, 2013, 2077, 2142, 2208, 2275 (list; graph; refs; listen; history; text; internal format)
 OFFSET 3,1 COMMENTS The number of diagonals for a convex polygon with n sides is n*(n-3)/2. For a triangle and a quadrilateral, the number of sides is greater than the number of diagonals. For a pentagon, the number of sides is equal to the number of diagonals. For an hexagon or a polygon with more than six sides, the number of diagonals is greater than the number of sides. LINKS Ask Dr. Math, Polygon diagonals Eric Weisstein's World of Mathematics, Polygon Eric Weisstein's World of Mathematics, Polygon diagonal FORMULA a(n) = n*(n-5)/2. CROSSREFS Cf. A000096 (number of diagonals of an n-gon). Cf. A006561 (number of intersections of diagonals in the interior of regular n-gon). Cf. A007678 (number of regions in regular n-gon with all diagonals drawn). Sequence in context: A231132 A290327 A131732 * A331922 A198826 A088161 Adjacent sequences:  A307678 A307679 A307680 * A307682 A307683 A307684 KEYWORD sign,easy AUTHOR Bernard Schott, Apr 21 2019 STATUS approved

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Last modified September 30 21:27 EDT 2020. Contains 337440 sequences. (Running on oeis4.)