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.

A243610 Irregular triangular array of all the integers, each exactly once, ordered as in Comments.

Original entry on oeis.org

1, 0, 2, -1, 4, -3, -2, 8, -7, -6, -4, 3, 16, -15, -14, -12, -8, 5, 6, 7, 32, -31, -30, -28, -24, -16, -5, 9, 10, 12, 13, 14, 15, 64, -63, -62, -60, -56, -48, -32, -13, -11, -10, -9, 17, 18, 20, 24, 25, 26, 28, 29, 30, 31, 128, -127, -126, -124, -120, -112
Offset: 1

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Author

Clark Kimberling, Jun 08 2014

Keywords

Comments

Let F = A000045 (the Fibonacci numbers). To construct the array, decree the first 4 rows as in the Example. Thereafter, row n consists of F(n) numbers in increasing order, generated as follows: the F(n-1) numbers 2*x from x in row n-1, together with the F(n-2) numbers 1 - 2*x from numbers x in row n-2. For n >= 3, row n consists of F(n-1) negative integers and F(n-2) positive integers; also, row n consists of F(n-1) even integers and F(n-2) odd integers. Conjecture: Every row contains F(k) or -F(k) for some k.

Examples

			First 7 rows of the array:
1
0 .... 2
-1 ... 4
-3 ... -2 ... 8
-7 ... -6 ... -4 ... 3 .... 16
-15 .. -14 .. -12 .. -8 ... 5 .... 6 ... 7 .. 32
-31 .. -30 .. -28 .. -24 .. -16 .. -5 .. 9 .. 10 . 12 . 13 . 14 . 15 . 64
		

Crossrefs

Programs

  • Mathematica
    z = 12; g[1] = {1}; f1[x_] := 2 x; f2[x_] := 1 - 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[g[n], {n, 1, 12}]
    v = Flatten[u]