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 A131976 Let G be the full icosahedral group, of order 120. Let v_1, ..., v_20 be the vertices of the dodecahedron. Let S(n) be the set of vectors v_{i_1} + v_{i_2} + ... + v_{i_n} where 1 <= i_1 <= i_2 <= ... <= i_n <= 20. Then a(n) = number of orbits of G on S(n). 1
 1, 1, 5, 12, 22, 34, 50, 65, 78, 78, 86, 78, 78, 65, 50, 34, 22, 12, 5, 1, 1 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,3 LINKS Table of n, a(n) for n=0..20. Wouter Meeussen, Excel spreadsheet EXAMPLE For 2 vertices, there are 5 different sets: {10 pairs with norm^2 of sum = 0.000} {30 pairs with 1.000} {60, 2.618} {60, 5.236} {30, 6.854} the norm^2 is taken with the side of the pentagons = 1. And of course 10+30+60+60+30 = 190 = 20 choose 2 CROSSREFS Sequence in context: A242338 A217649 A333578 * A074376 A293502 A134340 Adjacent sequences: A131973 A131974 A131975 * A131977 A131978 A131979 KEYWORD nonn,fini,full AUTHOR N. J. A. Sloane, Oct 06 2007, based on an email message from Wouter Meeussen on Dec 27 2004. EXTENSIONS More terms from Wouter Meeussen, Oct 07 2007 STATUS approved

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Last modified September 24 00:14 EDT 2023. Contains 365554 sequences. (Running on oeis4.)