The OEIS mourns the passing of Jim Simons and is grateful to the Simons Foundation for its support of research in many branches of science, including the OEIS.
The OEIS is supported by the many generous donors to the OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A243853 Number of numbers in row n of the array at A243851. 6
 1, 2, 2, 3, 5, 8, 12, 19, 30, 47, 75, 118, 187, 294, 465, 736, 1160, 1837, 2900, 4586, 7253, 11465, 18132, 28669, 45344, 71715, 113416, 179394, 283737, 448838, 709971, 1123055 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS Decree that (row 1) = (1) and (row 2) = (3,2). For n >= 4, row n consists of numbers in decreasing order generated as follows: x+1 for each x in row n-1 together with 3/x for each x in row n-1, and duplicates are rejected as they occur. Then a(n) = (number of numbers in row n); it appears that this sequence is not linearly recurrent. LINKS Table of n, a(n) for n=1..32. EXAMPLE First 6 rows of the array of rationals: 1/1 3/1 ... 2/1 4/1 ... 3/2 5/1 ... 5/2 ... 3/4 6/1 ... 7/2 ... 7/4 ... 6/5 ... 3/5 7/1 ... 9/2 ... 11/4 .. 11/5 .. 12/7 .. 8/5 .. 6/7 .. 1/2, so that A242453 begins with 1,2,2,3,5,8. MATHEMATICA z = 12; g[1] = {1}; f1[x_] := x + 1; f2[x_] := 3/x; h[1] = g[1]; b[n_] := b[n] = DeleteDuplicates[Union[f1[g[n - 1]], f2[g[n - 1]]]]; h[n_] := h[n] = Union[h[n - 1], g[n - 1]]; g[n_] := g[n] = Complement [b[n], Intersection[b[n], h[n]]] u = Table[Reverse[g[n]], {n, 1, z}]; v = Flatten[u]; Denominator[v] (* A243851 *) Numerator[v] (* A243852 *) Table[Length[g[n]], {n, 1, z}] (* A243853 *) CROSSREFS Cf. A243851, A243852, A243850. Sequence in context: A347546 A152948 A018136 * A293419 A277218 A293643 Adjacent sequences: A243850 A243851 A243852 * A243854 A243855 A243856 KEYWORD nonn,easy AUTHOR Clark Kimberling, Jun 12 2014 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified May 23 17:39 EDT 2024. Contains 372765 sequences. (Running on oeis4.)