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.

A109436 Triangle of numbers: row n gives the elements along the subdiagonal of A109435 that connects 2^n with (n+2)*2^(n-1).

Original entry on oeis.org

0, 0, 1, 1, 2, 3, 4, 7, 8, 8, 15, 19, 20, 16, 31, 43, 47, 48, 32, 63, 94, 107, 111, 112, 64, 127, 201, 238, 251, 255, 256, 128, 255, 423, 520, 558, 571, 575, 576, 256, 511, 880, 1121, 1224, 1262, 1275, 1279, 1280, 512, 1023, 1815, 2391, 2656, 2760, 2798, 2811
Offset: 0

Views

Author

Robert G. Wilson v, Jun 28 2005

Keywords

Comments

In the limit of row number n->infinity, the differences of the n-th row of the table, read from right to left, are 1, 4, 13, 38, 104,... = A084851.

Examples

			The triangle A109435 begins
    1;
    2,   1;
    4,   3,   1;
    8,   7,   3,   1;
   16,  15,   8,   3,   1;
   32,  31,  19,   8,   3,   1;
   64,  63,  43,  20,   8,   3,   1;
  128, 127,  94,  47,  20,   8,   3,   1;
If we read this triangle starting at 2^n in its first column along its n-th subdiagonal up to the first occurrence of (n+2)*2^(n-1), we get row n of the current triangle, which begins:
   0,   0;
   1,   1;
   2,   3;
   4,   7,   8;
   8,  15,  19,  20;
  16,  31,  43,  47,  48;
  32,  63,  94, 107, 111, 112;
		

Crossrefs

Programs

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

Extensions

Edited by R. J. Mathar, Nov 17 2009