A173111 - OEIS

A173111

Triangle read by rows, A173108 * the diagonalized variant of A173110

1, 1, 2, 1, 5, 1, 15, 2, 3, 52, 5, 3, 203, 15, 6, 6, 877, 52, 15, 6, 4140, 203, 45, 12, 20, 21147, 877, 156, 30, 20, 115975, 4140, 609, 90, 40, 60, 678570, 21147, 2631, 312, 100, 60

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OFFSET

0,3

COMMENTS

Row sums = A173110: (1, 1, 3, 6, 20, 60, 230, 950, 4420, 22230,...).

LINKS

Table of n, a(n) for n=0..41.

FORMULA

Let triangle A173108 = Q, and M = an infinite lower triangular matrix with A173110 as the rightmost diagonal and the rest zeros. Triangle A173111 = Q*M.

EXAMPLE

First few rows of the triangle =

2, 1;

5, 1;

15, 2, 3;

52, 5, 3;

203, 15, 6, 6;

877, 52, 15, 6;

4140, 203, 45, 12, 20;

21147, 877, 156, 30, 20;

115975, 4140, 609, 90, 40, 60;

678570, 21147, 2631, 312, 100, 60;