cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

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A386625 Rectangular array R, read by descending antidiagonals: (row m) = increasing sequence of numbers m*F(n), n>=2, without duplicates, where F = A000045 (Fibonacci numbers); see Comments.

Original entry on oeis.org

1, 2, 4, 3, 6, 9, 5, 10, 15, 12, 8, 16, 24, 20, 25, 13, 26, 39, 32, 40, 18, 21, 42, 63, 52, 65, 30, 7, 34, 68, 102, 84, 105, 48, 14, 64, 55, 110, 165, 136, 170, 78, 35, 104, 27, 89, 178, 267, 220, 275, 126, 56, 168, 45, 50, 144, 288, 432, 356, 445, 204, 91, 272, 72, 80, 11
Offset: 1

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Author

Clark Kimberling, Jul 27 2025

Keywords

Comments

Every positive integer appears exactly once. Every non-Fibonacci prime appears in the first column. Except for initial terms, every row is a row of the Wythoff array, A035513.

Examples

			Corner:
   1    2    3    5    8   13   21   34   55
   4    6   10   16   26   42   68  110  178
   9   15   24   39   63  102  165  267  432
  12   20   32   52   84  136  220  356  576
  25   40   65  105  170  275  445  720 1165
  18   30   48   78  126  204  330  534  864
   7   14   35   56   91  147  238  385  623
  64  104  168  272  440  712 1152  864 3016
  27   45   72  117  189  306  495  801 1296
  50   80  130  210  340  550  890 1440 2330
  11   22   33   88  143  231  374  605  979
  36   60   96  156  252  408  660 1068 1728
Row 4 is obtained from 4*(row 1) by removing 4 and 8.
		

Crossrefs

Cf. A000045, A005086 (counts removed duplicates), A035513, A386214.

Programs

  • Mathematica
    ClearAll[rArray]
    rArray[rows_, cols_] := Module[{fibs, R = {}, used = <||>, row, val, f, m},
       fibs = Map[Fibonacci, Range[2, cols + rows]];
       Table[row = {};
        Do[val = m*f; If[! KeyExistsQ[used, val], AppendTo[row, val];
          used[val] = True;], {f, fibs}]; Take[row, cols], {m, rows}]];
    Grid[rArray[16, 12], Frame -> All]  (* array *)
    r[m_, n_] := rArray[12, 12][[m]][[n]];
    Table[r[n - k + 1, k], {n, 1, 12}, {k, n, 1, -1}] // Flatten (*sequence*)
    (* Peter J. C. Moses, Jul 27 2025 *)

Formula

(row 1) = (1,2,3,5,8,13,...) = Fibonacci numbers, {F(n), n>=2}, and for m>1,
(row m) = numbers m*F(n) that are not h*F(k) for any h=2.
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