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.

A143956 Triangle read by rows, A000012 * A136521 * A000012; 1<=k<=n.

Original entry on oeis.org

1, 3, 2, 5, 4, 2, 7, 6, 4, 2, 9, 8, 6, 4, 2, 11, 10, 8, 6, 4, 2, 13, 12, 10, 8, 6, 4, 2, 15, 14, 12, 10, 8, 6, 4, 2, 17, 16, 14, 12, 10, 8, 6, 4, 2, 19, 18, 16, 14, 12, 10, 8, 6, 4, 2, 21, 20, 18, 16, 14, 12, 10, 8, 6, 4, 2
Offset: 1

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Comments

Row sums = A028387: (1, 5, 11, 19, 29, 41,...)

Examples

			First few rows of the triangle =
1;
3, 2;
5, 4, 2;
7, 6, 4, 2;
9, 8, 6, 4, 2;
11, 10, 8, 6, 4, 2;
13, 12, 10, 8, 6, 4, 2;
15, 14, 12, 10, 8, 6, 4, 2;
...
		

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Formula

Triangle read by rows, A000012 * A136521 * A000012; 1<=k<=n. A136521 = an infinite lower triangular matrix with (1,2,2,2,...) in the main diagonal the rest zeros.