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 A288849 Number of distinct rational numbers that can be obtained in n steps by a straight-line program (SLP) starting at 1 using addition, subtraction, multiplication and division. 3
 1, 3, 7, 21, 83, 484, 4084, 49479 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 LINKS EXAMPLE The sets of numbers obtainable at the n-th step are: S(0) = { 1 }, S(1) = { 0, 1, 2 }, S(2) = { -1, 0, 1/2, 1, 2, 3, 4 }, S(3) = { -3, -2, -3/2, -1, -1/2, 0, 1/4, 1/3, 1/2, 2/3, 1, 3/2, 2, 5/2, 3, 4, 5, 6, 8, 9, 16 }. CROSSREFS Cf. A214872, A288759, A288850. A216999 provides the corresponding results if division is not used. Sequence in context: A319123 A173794 A049365 * A031885 A259202 A169981 Adjacent sequences:  A288846 A288847 A288848 * A288850 A288851 A288852 KEYWORD nonn,hard,more AUTHOR Hugo Pfoertner, Jun 18 2017 EXTENSIONS a(7) from Alois P. Heinz, Jun 18 2017 STATUS approved

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Last modified September 20 12:42 EDT 2018. Contains 315239 sequences. (Running on oeis4.)