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 A060783 Number of conics which pass through 3 points and are bitangent to a general curve of order n. 1
 0, 0, 4, 36, 132, 340, 720, 1344, 2296, 3672, 5580, 8140, 11484, 15756, 21112, 27720, 35760, 45424, 56916, 70452, 86260, 104580, 125664, 149776, 177192, 208200, 243100, 282204, 325836, 374332, 428040, 487320, 552544, 624096, 702372, 787780 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,3 REFERENCES H. Brocard and T. Lemoyne: Courbes geometriques remarquables (courbes speciales) Planes et Gauches. Tome I, Paris: Albert Blanchard, 1967 [First publ. 1919]; see p. 411. Steiner, Crelle's J., Vol. 49, p. 273. LINKS Harry J. Smith, Table of n, a(n) for n=0,...,1000 FORMULA a(n) = (n-1)*n*(n^2 + 3*n - 6)/2. G.f.: 4*x^2*(1+4*x-2*x^2)/(1-x)^5. [Colin Barker, Mar 26 2012] PROG (PARI) { for (n=0, 1000, write("b060783.txt", n, " ", (n-1)*n*(n^2 + 3*n - 6)/2); ) } [From Harry J. Smith, Jul 11 2009] CROSSREFS Sequence in context: A144298 A072109 A045490 * A125756 A173961 A035287 Adjacent sequences:  A060780 A060781 A060782 * A060784 A060785 A060786 KEYWORD nonn,easy AUTHOR Antreas P. Hatzipolakis (xpolakis(AT)otenet.gr), Apr 28 2001 EXTENSIONS More terms from Jason Earls (zevi_35711(AT)yahoo.com), Apr 29 2001 STATUS approved

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