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.

A140068 Triangle read by rows, n-th row = (n-1)-th power of the matrix X * [1,0,0,0,...] where X = an infinite lower triangular matrix with [1,2,1,2,1,2,...] in the main diagonal and [1,1,1,...] in the subdiagonal.

Original entry on oeis.org

1, 1, 1, 1, 3, 1, 1, 7, 4, 1, 1, 15, 11, 6, 1, 1, 31, 26, 23, 7, 1, 1, 63, 57, 72, 30, 9, 1, 1, 127, 120, 201, 102, 48, 10, 1, 1, 255, 247, 522, 303, 198, 58, 12, 1, 1, 511, 502, 1291, 825, 699, 256, 82, 13, 1, 1, 1023, 1013, 3084, 2116, 2223, 955, 420, 95, 15, 1, 1, 2047, 2036
Offset: 1

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Author

Gary W. Adamson and Roger L. Bagula, May 04 2008

Keywords

Comments

Sum of n-th row terms = odd-indexed Fibonacci numbers, F(2n+1); e.g. sum of row 5 terms = (1 + 15 + 11 + 6 + 1) = 34 = F(9).
The triangle is a companion to A140069 (having row sums = even-indexed Fibonacci numbers).

Examples

			First few rows of the triangle are:
  1;
  1,   1;
  1,   3,   1;
  1,   7,   4,   1;
  1,  15,  11,   6,   1;
  1,  31,  26,  23,   7,   1;
  1,  63,  57,  72,  30,   9,   1;
  1, 127, 120, 201, 102,  48,  10,   1;
  1, 255, 247, 522, 303, 198,  58,  12,   1;
  ...
		

Crossrefs

Cf. A140069.

Formula

Triangle read by rows, n-th row = (n-1)-th power of the matrix X * [1,0,0,0,...] where X = an infinite lower triangular matrix with [1,2,1,2,1,2,...] in the main diagonal and [1,1,1,...] in the subdiagonal. Given the matrix X, perform X * [1,0,0,0,...] and then iterate: X * (result), etc. and record the result as each successive row of the triangle.