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.

A193739 Mirror of the triangle A193738.

Original entry on oeis.org

1, 1, 1, 2, 2, 1, 3, 3, 2, 1, 4, 4, 3, 2, 1, 5, 5, 4, 3, 2, 1, 6, 6, 5, 4, 3, 2, 1, 7, 7, 6, 5, 4, 3, 2, 1, 8, 8, 7, 6, 5, 4, 3, 2, 1, 9, 9, 8, 7, 6, 5, 4, 3, 2, 1, 10, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 11, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 12, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 13, 13, 12
Offset: 0

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Author

Clark Kimberling, Aug 04 2011

Keywords

Comments

This sequence is obtained by reversing the rows of the triangle A193738.
Except for the first term, this sequence gives the integers occurring in the song "One man went to mow".

Examples

			First six rows:
1
1....1
2....2....1
3....3....2....1
4....4....3....2...1
5....5....4....3...2...1
		

Crossrefs

Cf. A193738.

Programs

  • Haskell
    a193738 n k = a193738_tabl !! n !! k
    a193738_row n = a193738_tabl !! n
    a193738_tabl = map reverse a193739_tabl
    -- Reinhard Zumkeller, May 11 2013
  • Mathematica
    z = 12;
    p[0, x_] := 1
    p[n_, x_] := x*p[n - 1, x] + 1; p[n_, 0] := p[n, x] /. x -> 0
    q[n_, x_] := p[n, x]
    t[n_, k_] := Coefficient[p[n, x], x^(n - k)];
    t[n_, n_] := p[n, x] /. x -> 0;
    w[n_, x_] := Sum[t[n, k]*q[n + 1 - k, x], {k, 0, n}]; w[-1, x_] := 1
    g[n_] := CoefficientList[w[n, x], {x}]
    TableForm[Table[Reverse[g[n]], {n, -1, z}]]
    Flatten[Table[Reverse[g[n]], {n, -1, z}]]  (* A193738 *)
    TableForm[Table[g[n], {n, -1, z}]]
    Flatten[Table[g[n], {n, -1, z}]]   (* A193739 *)

Formula

Write w(n,k) for the triangle at A193738. The current triangle is then given by w(n,n-k).