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 A337790 Number of vertices in a Y-shaped polygon with equal arms of length n (see the Comments in A335861 for definition). 2
 3, 57, 306, 837, 1335, 2073, 3033, 4395, 6147, 8469, 11253, 14907, 19263, 24819, 31197, 38823, 47619 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,1 COMMENTS See A335861 for a definition of the polygon and images for the number of regions. LINKS Scott R. Shannon, Image for the figure showing the vertex counts for n=1. Scott R. Shannon, Image for the figure showing the vertex counts for n=2. Scott R. Shannon, Image for the figure showing the vertex counts for n=3. Scott R. Shannon, Image for the figure showing the vertex counts for n=4. Scott R. Shannon, Image for the figure showing the vertex counts for n=5. Scott R. Shannon, Image for the figure showing the vertex counts for n=6. EXAMPLE a(0) = 3. A single triangle with no other polygons has three vertices. a(1) = 57. With one square adjacent to each of the triangles sides the resulting line segments form 51 vertices shared by four polygons, 3 vertices shared by six polygons, and 3 vertices shared by seven polygons. This gives a total of 57 vertices. See the first linked image. CROSSREFS Cf. A335861 (number of regions), A331456, A331452, A306302, A092867, A007678. Sequence in context: A122548 A078728 A032696 * A131466 A171356 A060483 Adjacent sequences:  A337787 A337788 A337789 * A337791 A337792 A337793 KEYWORD nonn,more AUTHOR Scott R. Shannon and N. J. A. Sloane, Sep 22 2020 STATUS approved

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Last modified September 29 16:15 EDT 2022. Contains 357090 sequences. (Running on oeis4.)