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 A066372 Number of different shapes formed by bending a piece of wire of length n in the plane. 2
 1, 1, 2, 3, 5, 8, 15, 23, 43, 71, 128, 209, 379, 650, 1145, 1928, 3422, 5908, 10295, 17530, 30738, 53088, 91971 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,3 COMMENTS Wire is marked into n equal segments by n-1 marks, is bent at right angles at each of these points, making each segment parallel to one of two rectangular axes. (Stays in plane, bends are of +-90 degs.) May cross itself but is not self-coincident over a finite length. Two configurations which differ only in a rotation or turning over are not counted as different. REFERENCES Deborah Freedman, dlf(AT)alumni.princeton.edu, personal communication. LINKS Erich Friedman, Illustration of initial terms EXAMPLE Let LRUD denote left, right, up, down. Then for n = 1..4 the solutions are R, RD, RDL, RDR, RDLU, RDLD, RDRD. For n=5 the 5 shapes are __.__. __....__ |__.... .__.... __...... ..|__| ..|__|.. ...|__| |..|__| ..|__... ...... ........ ....... ....... .....|__ CROSSREFS See A001997 for another version. Sequence in context: A104880 A152478 A102973 * A058519 A181065 A282239 Adjacent sequences:  A066369 A066370 A066371 * A066373 A066374 A066375 KEYWORD more,nonn,nice AUTHOR Richard D. Plotz (Dick(AT)Plotz.com), Dec 22 2001 EXTENSIONS a(10)-a(23) from Nathaniel Johnston, Jan 04 2011 STATUS approved

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Last modified January 21 02:59 EST 2019. Contains 319344 sequences. (Running on oeis4.)