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.

A130125 Triangle defined by A128174 * A130123, read by rows.

Original entry on oeis.org

1, 0, 2, 1, 0, 4, 0, 2, 0, 8, 1, 0, 4, 0, 16, 0, 2, 0, 8, 0, 32, 1, 0, 4, 0, 16, 0, 64, 0, 2, 0, 8, 0, 32, 0, 128, 1, 0, 4, 0, 16, 0, 64, 0, 256, 0, 2, 0, 8, 0, 32, 0, 128, 0, 512, 1, 0, 4, 0, 16, 0, 64, 0, 256, 0, 1024, 0, 2, 0, 8, 0, 32, 0, 128, 0, 512, 0, 2048
Offset: 0

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Author

Gary W. Adamson, May 11 2007

Keywords

Comments

Row sums = A000975: (1, 2, 5, 10, 21, 42, ...).

Examples

			First few rows of the triangle are:
  1;
  0, 2;
  1, 0, 4;
  0, 2, 0, 8;
  1, 0, 4, 0, 16;
  0, 2, 0, 8,  0, 32; ...
		

Crossrefs

Programs

  • GAP
    Flat(List([0..10], n-> List([0..n], k-> 2^(k-1)*(1+(-1)^(n-k)) ))); # G. C. Greubel, Jun 05 2019
  • Magma
    [[2^(k-1)*(1+(-1)^(n-k)): k in [0..n]]: n in [0..10]]; // G. C. Greubel, Jun 05 2019
    
  • Mathematica
    Table[2^(k-1)*(1+(-1)^(n-k)), {n,0,10}, {k,0,n}]//Flatten (* G. C. Greubel, Jun 05 2019 *)
  • PARI
    {T(n,k) = 2^(k-1)*(1+(-1)^(n-k))}; \\ G. C. Greubel, Jun 05 2019
    
  • Sage
    [[2^(k-1)*(1+(-1)^(n-k)) for k in (0..n)] for n in (0..10)] # G. C. Greubel, Jun 05 2019
    

Formula

A128174 * A130123 as infinite lower triangular matrices. By columns, (2^k, 0, 2^k, 0, ...).
T(n,k) = 2^(k-1)*(1 + (-1)^(n-k)). - G. C. Greubel, Jun 05 2019

Extensions

More terms added by G. C. Greubel, Jun 05 2019