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 A130896 For D_n type groups as polyhedra that are pyramid-like: {F,V,E,dimension}->{2*n+1,2*n+1,2*n,(2*n+1)*((2*n+1)-1)/2} such that Euler's equation is true: V=E-F+2. 0
 3, 3, 4, 3, 5, 5, 8, 10, 7, 7, 12, 21, 9, 9, 16, 36, 11, 11, 20, 55, 13, 13, 24, 78, 15, 15, 28, 105, 17, 17, 32, 136, 19, 19, 36, 171, 21, 21, 40, 210, 23, 23, 44, 253, 25, 25, 48, 300, 27, 27, 52, 351, 29, 29, 56, 406, 31, 31, 60, 465, 33, 33, 64, 528, 35, 35, 68, 595, 37, 37 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS This idea comes from the Octahedron being truncated by one vertex to give a pyramid. In this case the n=1 is not a 3d polyhedron, but the rest are very simple F=E figures. Adding one vertex below the plane of the major polygon gives an D_nh type point group ( D_n like figures A131498): these figures are Point groups C_nv. REFERENCES David M. Bishop, Group Theory and Chemistry,Dover Publications, 1993, table 3-7.1, page 46 LINKS FORMULA {a(n),a(n+1),a(n+2),a(n+3) = {2*m+1,2*m+1,4*m,(2*m+1)*((2*m+1)-1)/2}: m=Floor[n/4] MATHEMATICA a = Table[{2*n + 1, 2*n + 1, 4*n, (2*n + 1)*((2*n + 1) - 1)/2}, {n, 1, 32}]; Flatten[a] CROSSREFS Cf. A131498. Sequence in context: A316662 A123708 A102302 * A254279 A029882 A163523 Adjacent sequences:  A130893 A130894 A130895 * A130897 A130898 A130899 KEYWORD nonn AUTHOR Roger L. Bagula, Aug 22 2007 STATUS approved

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Last modified September 19 12:57 EDT 2019. Contains 327198 sequences. (Running on oeis4.)