OFFSET
0,3
LINKS
Wikipedia, Involution
FORMULA
T(2n+1,n) = A072187(n+1).
EXAMPLE
T(5,0) = 5: 12345, 21345, 32145, 43215, 54321.
T(5,1) = 18: 12354, 12435, 12543, 13245, 14325, 14523, 15432, 21354, 21435, 21543, 32154, 34125, 42315, 42513, 45312, 52341, 52431, 53241.
T(5,2) = 3: 13254, 15342, 35142.
Triangle T(n,k) begins:
1;
1;
2;
3, 1;
4, 6;
5, 18, 3;
6, 44, 26;
7, 91, 123, 11;
8, 172, 448, 136;
9, 300, 1348, 912, 51;
10, 496, 3600, 4552, 838;
11, 781, 8704, 18476, 7441, 283;
12, 1186, 19584, 65324, 48116, 5930;
13, 1742, 41379, 206556, 250375, 66606, 1833;
CROSSREFS
KEYWORD
nonn,tabf
AUTHOR
Alois P. Heinz, Apr 27 2018
STATUS
approved