A092081 Triangle of certain double factorials.

1, 1, 2, 1, 3, 8, 1, 4, 15, 48, 1, 5, 24, 105, 384, 1, 6, 35, 192, 945, 3840, 1, 7, 48, 315, 1920, 10395, 46080, 1, 8, 63, 480, 3465, 23040, 135135, 645120, 1, 9, 80, 693, 5760, 45045, 322560, 2027025, 10321920, 1, 10, 99, 960, 9009, 80640, 675675, 5160960

Offset: 0

Author

Wolfdieter Lang, Mar 19 2004

Keywords

• nonn
• easy
• tabl

Comments

This is the rectangular array A(3;m,n) := (2*n+m)!!/m!!, m >= 0, n >= 0, read by SW-NE diagonals. For n!! see A006882 (double factorials).

Links

• W. Lang, First 9 rows.

Crossrefs

Diagonals give: A000165 (double factorials of 2*n), A001147(n+1), A002866, A051577-83.

Columns give: A000012 (powers of 1), A000027 (naturals >=2), A005563, 3*A077415, for n=0..3.

Formula

a(m, n)=(n+m)!!/(m-n)!!, 0<=n<=m, else 0, with 0!! := 1.