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.

A127651 Triangle T(n,k) = n*k if k|n, 0 otherwise; 1<=k<=n.

Original entry on oeis.org

1, 2, 4, 3, 0, 9, 4, 8, 0, 16, 5, 0, 0, 0, 25, 6, 12, 18, 0, 0, 36, 7, 0, 0, 0, 0, 0, 49, 8, 16, 0, 32, 0, 0, 0, 64, 9, 0, 27, 0, 0, 0, 0, 0, 81, 10, 20, 0, 0, 50, 0, 0, 0, 0, 100, 11, 0, 0, 0, 0, 0, 0, 0, 0, 0, 121, 12, 24, 36, 48, 0, 72, 0, 0, 0, 0, 0, 144
Offset: 1

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Author

Gary W. Adamson, Jan 22 2007

Keywords

Comments

Equals the matrix product A127648 * A127093 as infinite lower triangular matrices.

Examples

			First few rows of the triangle are:
1;
2, 4;
3, 0, 9;
4, 8, 0, 16;
5, 0, 0, 0, 25;
6, 12, 18, 0, 0, 36;
7, 0, 0, 0, 0, 0, 49;
8, 16, 0, 32, 0, 0, 0, 64;
...
		

Crossrefs

Cf. A127648, A127093, A064987 (row sums).

Programs

  • Maple
    A127651 := proc(n,k)
            if n mod k =0 then
                    n*k;
            else
                    0 ;
            end if;
    end proc: # R. J. Mathar, Oct 01 2011

Formula

T(n,k) = n*A127093(n,k). - R. J. Mathar, Oct 01 2011