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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.

A141290 Triangle read by rows, descending antidiagonals of a (1, 3, 5, ...) * (1, 4, 16, ...) multiplication table.

Original entry on oeis.org

1, 3, 4, 5, 12, 16, 7, 20, 48, 64, 9, 28, 80, 192, 256, 11, 36, 112, 320, 768, 1024, 13, 44, 144, 448, 1280, 3072, 4096, 15, 52, 176, 576, 1792, 5120, 12288, 16384, 17, 60, 208, 704, 2304, 7168, 20480, 49152, 65536, 19, 68, 240, 832, 2816, 9216, 28672, 81920, 196608, 262144
Offset: 1

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Author

Gary W. Adamson, Jun 22 2008

Keywords

Comments

Binary representation of all terms ends in an even number of zeros (cf. A003159).

Examples

			Given the multiplication table (1, 3, 5, ...) * (1, 4, 16, ...); i.e., odd numbers as column headings, powers of 4 along the left border:
   1,   3,   5,   7, ...
   4,  12,  20,  28, ...
  16,  48,  80, 112, ...
  64, 192, 320, 448, ...
  ...
Rows of the triangle = descending antidiagonals of the array, getting:
   1;
   3,  4;
   5, 12,  16;
   7, 20,  48,  64;
   9, 28,  80, 192,  256;
  11, 36, 112, 320,  768, 1024;
  13, 44, 144, 448, 1280, 3072,  4096;
  15, 52, 176, 576, 1792, 5120, 122288, 16384;
  ...
		

Crossrefs

Programs

  • Mathematica
    A[n_,k_]:=(2k-1)*4^(n-1); Table[A[k,n-k+1],{n,10},{k,n}]//Flatten (* Stefano Spezia, May 21 2024 *)

Formula

From Stefano Spezia, May 21 2024: (Start)
G.f. as array: x*y*(1 + y)/((1 - 4*x)*(1 - y)^2).
E.g.f. as array: (exp(4*x) - 1)*(exp(y)*(1 - 2*y) - 1)/4. (End)

Extensions

a(14), a(36) corrected by Peter Munn, Aug 27 2019