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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A307693 Rectangular quotient array, R, of A003188 read by descending antidiagonals; see Comments.

Original entry on oeis.org

1, 3, 1, 2, 3, 1, 6, 2, 2, 1, 7, 6, 4, 3, 1, 5, 7, 5, 2, 3, 1, 4, 5, 3, 6, 2, 2, 1, 12, 4, 8, 7, 5, 4, 2, 1, 13, 12, 9, 5, 6, 5, 4, 3, 1, 15, 13, 10, 4, 4, 3, 3, 2, 3, 1, 14, 15, 7, 12, 10, 8, 7, 6, 2, 3, 1, 10, 14, 6, 13, 11, 9, 9, 7, 6, 2, 2, 1, 11, 10, 16
Offset: 1

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Author

Clark Kimberling, Oct 26 2019

Keywords

Comments

Suppose that P = (p(m)) is a permutation of the positive integers, such as A038722. For each n >= 1, let q(n,k) be the k-th index m such that n divides p(m), and let r(n) = p(q(n,k))/n. Let R be the array having (r(n)) as row n. We call R the quotient array of P. Every row of R is a permutation of the positive integers.
In the present case that P = A003188, every row occurs infinitely many times. Specifically, if p is a prime (A000040), then for every multiple m*p of p, the rows numbered m*p are identical. See A327314 for the array that results by deleting duplicate rows from R.

Examples

			A003188 = (1, 3, 2, 6, 7, 5, 4, 12, 13, 15, 14, 10, 11, 9, 8, 24, 25, 27, 26, 30, 31, 29, 28, 20, ...)
Row 1 of R is just A003188. To get row 2 of R, skip the odds in A003188 and divide the evens by 2; row 2 equals row 1. Generally, to get row n, divide A003188 by n and then delete the non-integers.
________________
Northwest corner of R:
  1   3   2   6   7   5    4   12   13   15
  1   3   2   6   7   5    4   12   13   15
  1   2   4   5   3   8    9   10    7    6
  1   3   2   6   7   5    4   12   13   15
  1   3   2   5   6   4   10   11   12    8
  1   2   4   5   3   8    9   10    7    6
		

Crossrefs

Programs

  • Mathematica
    s = Table[BitXor[n, Floor[n/2]], {n, 300}]  (* A003188 *)
    g[n_] := Flatten[Position[Mod[s, n], 0]];
    u[n_] := s[[g[n]]]/n;
    TableForm[Table[Take[u[n], 10], {n, 1, 20}]]  (* A307693 array *)
    v[n_, k_] := u[n][[k]]
    Table[v[n - k + 1, k], {n, 14}, {k, n, 1, -1}] // Flatten (* A307693 sequence *)
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