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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A227984 Triangle T(n,k), read by rows: T(n,k) is the numerator of (1-2^(n-k+1))/(1-2^(k+1)).

Original entry on oeis.org

1, 3, 1, 7, 1, 1, 15, 7, 3, 1, 31, 5, 1, 1, 1, 63, 31, 15, 7, 3, 1, 127, 21, 31, 1, 7, 1, 1, 255, 127, 9, 31, 15, 1, 3, 1, 511, 85, 127, 21, 1, 5, 7, 1, 1, 1023, 511, 255, 127, 63, 31, 15, 7, 3, 1, 2047, 341, 73, 17, 127, 1, 31, 1, 1, 1, 1, 4095, 2047, 1023
Offset: 0

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Author

Vincenzo Librandi, Aug 12 2013

Keywords

Comments

The denominators are given in A228035.
The first column is A000225, the second column is A213243, and the third column is A213245.

Examples

			Triangle begins:
1;
3,     1;
7,     1,  1;
15,    7,  3,    1;
31,    5,  1,    1,  1;
63,   31,  15,   7,  3,  1;
127,  21,  31,   1,  7,  1,  1;
255,  127,  9,   31, 15, 1,  3,  1;
511,  85,  127,  21, 1,  5,  7,  1, 1;
1023, 511, 255, 127, 63, 31, 15, 7, 3, 1;
2047, 341, 73,   17, 127, 1, 31, 1, 1, 1, 1; etc.
		

Crossrefs

Programs

  • Magma
    [Numerator((1-2^(n-k+1))/(1-2^(k+1))): k in [0..n], n in [0..11]];
  • Mathematica
    a[n_, k_] := Numerator[(1 - 2^(n - k + 1))/(1 - 2^(k + 1))];
    Table[a[n, k], {n, 0, 11}, {k, 0, n}] // Flatten
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