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.

A128222 A127701 * A128174.

Original entry on oeis.org

1, 1, 2, 3, 1, 3, 1, 4, 1, 4, 5, 1, 5, 1, 5, 1, 6, 1, 6, 1, 6, 7, 1, 7, 1, 7, 1, 7, 1, 8, 1, 8, 1, 8, 1, 8, 9, 1, 9, 1, 9, 1, 9, 1, 9, 1, 10, 1, 10, 1, 10, 1, 10, 1, 10
Offset: 1

Views

Author

Gary W. Adamson, Feb 19 2007

Keywords

Comments

Row sums = A128223: (1, 3, 7, 10, 17, 21, 31, 36, ...).

Examples

			First few rows of the triangle:
  1;
  1, 2;
  3, 1, 3;
  1, 4, 1, 4;
  5, 1, 5, 1, 5;
  1, 6, 1, 6, 1, 6;
  7, 1, 7, 1, 7, 1, 7;
  ...
		

Crossrefs

Programs

  • Mathematica
    a128222[n_, k_] := If[EvenQ[n-k], n, 1]/;1<=k<=n
    a128222[r_] := Table[a128222[n, k], {n, 1, r}, {k, 1, n}]
    TableForm[a128222[7]] (* triangle *)
    Flatten[a128222[10]] (* data *) (* Hartmut F. W. Hoft, Mar 08 2017 *)

Formula

A127701 * A128174 as infinite lower triangular matrices. Odd rows: n terms of n, 1, n, ...; even rows: n terms of 1, n, 1, ...

Extensions

Inserted omitted values a(28) = 7 and a(29) = 1, Hartmut F. W. Hoft, Mar 08 2017