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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A158906 Triangle read by rows: the matrix product A158821 * A051731.

Original entry on oeis.org

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

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Author

Gary W. Adamson and Mats Granvik, Mar 29 2009

Keywords

Examples

			First few rows of the triangle =
1;
2, 1;
3, 0, 1;
4, 1, 0, 1;
5, 0, 0, 0, 1;
6, 1, 1, 0, 0, 1;
7, 0, 0, 0, 0, 0, 1;
8, 1, 0, 1, 0, 0, 0, 1;
9, 0, 1, 0, 0, 0, 0, 0, 1;
10, 1, 0, 0, 1, 0, 0, 0, 0, 1;
11, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1;
12, 1, 1, 1, 0, 1, 0, 0, 0, 0, 0, 1;
13, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1;
...
		

Crossrefs

Cf. A158821, A051731, A158907 (row sums).

Programs

  • Maple
    N:= 20: # to get the first N rows
    M1:= Matrix(N,N, shape = triangular[lower]);
    M1[..,1] := Vector([$0..N-1]);
    M1:= M1 + LinearAlgebra:-IdentityMatrix(N);
    M2:= Matrix(N,N, shape=triangular[lower],(i,j) -> charfcn[0](i mod j));
    M:= M1 . M2;
    seq(seq(M[i,j],j=1..i),i=1..N); # Robert Israel, Jan 08 2015

Formula

Triangle read by rows, A158821 * A051731, where A051731 = the inverse Mobius transform.
T(n,k) = A051731(n,k) if k>1.
T(n,1) = n.
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