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.

A075993 Triangle read by rows: T(n,m) is the number of integers k such that floor(n/k) = m, n >= 1, k = 1..n.

Original entry on oeis.org

1, 1, 1, 2, 0, 1, 2, 1, 0, 1, 3, 1, 0, 0, 1, 3, 1, 1, 0, 0, 1, 4, 1, 1, 0, 0, 0, 1, 4, 2, 0, 1, 0, 0, 0, 1, 5, 1, 1, 1, 0, 0, 0, 0, 1, 5, 2, 1, 0, 1, 0, 0, 0, 0, 1, 6, 2, 1, 0, 1, 0, 0, 0, 0, 0, 1, 6, 2, 1, 1, 0, 1, 0, 0, 0, 0, 0, 1, 7, 2, 1, 1, 0, 1, 0, 0, 0, 0, 0, 0, 1, 7, 3, 1, 1, 0, 0, 1, 0, 0, 0, 0, 0, 0, 1
Offset: 1

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Author

Clark Kimberling, Sep 28 2002

Keywords

Comments

The sum of numbers in row n is n.
Number of terms > 0 per row: Sum_{k=1..n} A057427(T(n,k)) = A055086(n). - Reinhard Zumkeller, Apr 06 2006

Examples

			T(5, 1) = 3 counts k such that floor(5/k) = 1, namely k = 5, 4, 3.
First 10 rows:
  1
  1 1
  2 0 1
  2 1 0 1
  3 1 0 0 1
  3 1 1 0 0 1
  4 1 1 0 0 0 1
  4 2 0 1 0 0 0 1
  5 1 1 1 0 0 0 0 1
  5 2 1 0 1 0 0 0 0 1
		

Crossrefs

Columns 1, 2, 3 are essentially A004526, A008615, A008679.
Cf. A010766.

Programs

  • Mathematica
    Table[Floor[n/m] - Floor[n/(m + 1)], {n, 14}, {m, n}] // Flatten (* Michael De Vlieger, Jan 14 2022 *)

Formula

T(n, m) = floor(n/m) - floor(n/(m+1)).