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.

A109434 Irregular triangle read by rows: row n contains the numbers from 2^n up to (n+3)*2^(n-2), inclusive, read along their common subdiagonal of A109433.

Original entry on oeis.org

0, 0, 1, 1, 2, 2, 4, 5, 8, 11, 12, 16, 24, 27, 28, 32, 51, 60, 63, 64, 64, 107, 131, 140, 143, 144, 128, 222, 282, 307, 316, 319, 320, 256, 457, 601, 666, 691, 700, 703, 704, 512, 935, 1270, 1432, 1498, 1523, 1532, 1535, 1536, 1024, 1904, 2665, 3057, 3224, 3290
Offset: 0

Views

Author

Robert G. Wilson v, Jun 28 2005

Keywords

Comments

Evolution of 2^n into 2^(n-2)(n+3) as exhibited by A109433.
The forward differences of the last row of the table approache A058396.

Examples

			Triangle begins
   0  0
   1  1
   2  2
   4  5
   8 11 12
  16 24 27 28
  32 51 60 63 64
		

Crossrefs

Programs

  • Mathematica
    T[n_, m_] := Length[ Select[ StringPosition[ #, ToString[(10^m - 1)/9]] & /@ Table[ ToString[ FromDigits[ IntegerDigits[i, 2]]], {i, 2^n, 2^(n + 1) - 1}], # != {} &]]; Join[{0, 0, 1, 1, 2}, Flatten[ Table[ T[n + i, i], {n, 0, 9}, {i, n + 1}]]]

Extensions

New definition from R. J. Mathar, Nov 27 2007