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.

A143865 Eigentriangle of A099375 (odd number subsequences decrescendo).

Original entry on oeis.org

1, 3, 1, 5, 3, 4, 7, 5, 12, 12, 9, 7, 20, 36, 36, 11, 9, 28, 60, 108, 108, 13, 11, 36, 84, 180, 324, 324, 15, 13, 44, 108, 252, 540, 972, 972, 17, 15, 52, 132, 324, 756, 1620, 2916, 2916
Offset: 1

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Author

Gary W. Adamson, Sep 04 2008

Keywords

Comments

The product A099375 * (A003946 * 0^(n-k)) creates a new eigentriangle with rows = termwise product of odd descrendo terms, e.g.: (7, 5, 3, 1) and first n terms of (1, 1, 4, 12,). The resulting triangle has row sums = (1, 4, 12, 36, 108,...), right border = (1, 1, 4, 12, 36,...) and the property that sum of n-th row terms = rightmost term of next row.

Examples

			First few rows of the triangle = 1; 3, 1; 5, 3, 4; 7, 5, 12, 12; 9, 7, 20, 36, 36; 11, 9, 28, 60, 108, 108; 13, 11, 36, 84, 180, 324, 324; ... Row 4 = termwise product of (7, 5, 3, 1) and (1, 1, 4, 12) = (7*1, 5*1, 3*4, 1*12).
		

Crossrefs

Formula

Triangle read by rows, A099375: (1; 3,1; 5,3,1;...) * (A003946 * 0^(n-k)); 1<=k<=n. (A003946 * 0^(n-k) = an infinite lower triangular matrix with shifted A003946: (1, 1, 4, 12, 36, 108,...) in the main diagonal and the rest zeros.