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 A256940 a(n) is the total number of free ends of a certain configuration of line segments after n iterations (see Comments lines for definition). 2
 2, 4, 8, 12, 12, 12, 20, 20, 16, 24, 28, 48, 52, 36, 44, 36, 16, 24, 40, 56, 72, 72, 76, 80, 60, 64, 80, 120, 132, 88, 100, 68, 16, 24, 40, 56, 72, 80, 88, 104, 112, 128, 176, 216, 244, 212, 168, 148, 84, 64, 104, 152, 200, 200, 212, 216, 148, 144, 176, 276, 292, 192, 212, 132, 16 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,1 COMMENTS The initial pattern is a straight line segment which has 2 free ends: a(0)=2. The construction rules for the following generations are: (i) add 2 line segments (all line segments are of equal length) at each free end of previous generation by arranging them in a "V" shape at angle Pi/2 and symmetrically placed at the free end, (ii) overlaps among different generations are prohibited, (iii) the {a(n)} free ends are the ends of elements that do not toucht or cross the others. It seems that a(n) drop to 16 for n = 8, 16, 32, 64,... . See illustration in the links. The structure of the illustration of initial terms is very similar to the structure of A194270 and A220500. The terms of this sequence should be checked! - Omar E. Pol, Apr 19 2015 LINKS Kival Ngaokrajang, Illustration of initial terms, n <= 12 Kival Ngaokrajang, Illustration  for a(64)=16 CROSSREFS Cf. A194270, A194440, A194442, A220500, A220520, A220522, A256641, A256941. Sequence in context: A009507 A064657 A182837 * A048314 A118286 A211823 Adjacent sequences:  A256937 A256938 A256939 * A256941 A256942 A256943 KEYWORD nonn AUTHOR Kival Ngaokrajang, Apr 19 2015 EXTENSIONS a(1) = 2 prepended and a(3) = 8 corrected by Omar E. Pol, Apr 19 2015 Partially edited by Kival Ngaokrajang, as Omar E. Pol suggestion, Apr 26 2015 Terms a(12), a(13), a(59) corrected by Kival Ngaokrajang, Apr 26 2015 STATUS approved

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Last modified June 2 11:20 EDT 2020. Contains 334771 sequences. (Running on oeis4.)