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.

Showing 1-3 of 3 results.

A114006 Row sums of number triangle A114004.

Original entry on oeis.org

1, -1, -1, 1, -1, 3, -1, -1, 1, 3, -1, -5, -1, 3, 3, 1, -1, -5, -1, -5, 3, 3, -1, 7, 1, 3, -1, -5, -1, -13, -1, -1, 3, 3, 3, 13, -1, 3, 3, 7, -1, -13, -1, -5, -5, 3, -1, -9, 1, -5, 3, -5, -1, 7, 3, 7, 3, 3, -1, 31, -1, 3, -5, 1, 3, -13, -1, -5, 3, -13, -1, -25, -1, 3, -5, -5, 3, -13, -1, -9, 1, 3, -1, 31, 3, 3, 3, 7, -1, 31, 3, -5, 3, 3, 3, 11
Offset: 1

Views

Author

Paul Barry, Nov 12 2005

Keywords

Comments

A signed version of A050328.

Crossrefs

Programs

  • Mathematica
    a050328[n_]:=If[n==1, n, Sum[If[(dIndranil Ghosh, May 27 2017 *)
  • PARI
    A050328(n) = if(1==n,n,sumdiv(n,d,if((dA050328(d),0)));
    A114006(n) = ((-1)^bigomega(n) * A050328(n)); \\ Antti Karttunen, May 27 2017

Formula

a(n) = A008836(n) * A050328(n). - Antti Karttunen, May 27 2017
a(1) = 1; a(n) = Sum_{d|n, d < n} mu(n/d) * a(d). - Ilya Gutkovskiy, Feb 23 2020

Extensions

More terms, incorrect formulas replaced by a correct one - Antti Karttunen, May 27 2017

A114005 First column of number triangle A114004.

Original entry on oeis.org

1, -2, -2, 2, -2, 6, -2, -2, 2, 6, -2, -10, -2, 6, 6, 2, -2, -10, -2, -10, 6, 6, -2, 14, 2, 6, -2, -10, -2, -26, -2, -2, 6, 6, 6, 26, -2, 6, 6, 14, -2, -26, -2, -10, -10, 6, -2, -18, 2, -10, 6, -10, -2, 14, 6, 14, 6, 6, -2, 62, -2, 6, -10, 2, 6, -26, -2, -10, 6, -26, -2, -50, -2, 6, -10, -10, 6, -26, -2, -18, 2, 6, -2, 62, 6, 6, 6, 14, -2, 62, 6, -10, 6, 6, 6
Offset: 1

Views

Author

Paul Barry, Nov 12 2005

Keywords

Comments

Moebius transform of A114006. - Mats Granvik, Jan 02 2009

Crossrefs

Programs

Formula

a(1) = 1, for n > 1, a(n) = 2*A114006(n). - Corrected by Antti Karttunen, May 27 2017
a(1) = 1; a(n) = -2 * Sum_{d|n, d < n} a(d). - Ilya Gutkovskiy, Feb 23 2020

Extensions

More terms from Antti Karttunen, May 27 2017

A114002 Expansion of g.f. x^k(1+x^(k+1))/(1-x^(k+1)).

Original entry on oeis.org

1, 2, 1, 2, 0, 1, 2, 2, 0, 1, 2, 0, 0, 0, 1, 2, 2, 2, 0, 0, 1, 2, 0, 0, 0, 0, 0, 1, 2, 2, 0, 2, 0, 0, 0, 1, 2, 0, 2, 0, 0, 0, 0, 0, 1, 2, 2, 0, 0, 2, 0, 0, 0, 0, 1, 2, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 2, 2, 2, 2, 0, 2, 0, 0, 0, 0, 0, 1, 2, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 2, 2, 0, 0, 0, 0, 2, 0, 0, 0, 0, 0, 0, 1
Offset: 0

Views

Author

Paul Barry, Nov 12 2005

Keywords

Comments

Inverse is A114004. Row sums are A114003.

Examples

			Triangle begins:
  1;
  2, 1;
  2, 0, 1;
  2, 2, 0, 1;
  2, 0, 0, 0, 1;
  2, 2, 2, 0, 0, 1;
  2, 0, 0, 0, 0, 0, 1;
  ...
		

Crossrefs

Programs

  • Mathematica
    T[n_,k_]:=SeriesCoefficient[x^k(1+x^(k+1))/(1-x^(k+1)),{x,0,n}]; Table[T[n,k],{n,0,13},{k,0,n}] //Flatten (* Stefano Spezia, Sep 08 2023 *)

Formula

Column k has g.f. x^k(1+x^(k+1))/(1-x^(k+1)).
Equals 2*A051731 - I, I = Identity matrix. - Gary W. Adamson, Nov 07 2007
Showing 1-3 of 3 results.