OFFSET
0,8
COMMENTS
Column with index 1 forms the row sums shift right. The convergent of the rows in reverse order is the Catalan sequence (A000108).
FORMULA
T(n, k) = Sum_{i=0..n-1} T(n-2, i)*T(i, k-1) for n>1 and k>0; T(n, 0)=T(n, n)=1.
EXAMPLE
Rows begin:
[1],
[1,1],
[1,1,1],
[1,2,1,1],
[1,3,2,1,1],
[1,5,5,2,1,1],
[1,8,10,5,2,1,1],
[1,15,22,14,5,2,1,1],
[1,28,47,34,14,5,2,1,1],
[1,61,113,88,42,14,5,2,1,1],
[1,133,269,223,116,42,14,5,2,1,1],...
The matrix square of T is given by:
[1],
[2,1],
[3,2,1],
[5,5,2,1],
[8,10,5,2,1],
[15,22,14,5,2,1],
[28,47,34,14,5,2,1],
[61,113,88,42,14,5,2,1],
[133,269,223,116,42,14,5,2,1],...
which equals T shift one place diagonally left and upward.
PROG
(PARI) T(n, k)=if(n<k || k<0, 0, if(n==k || k==0, 1, sum(i=0, n-1, T(n-2, i)*T(i, k-1)); ))
CROSSREFS
KEYWORD
nonn,tabl
AUTHOR
Paul D. Hanna, Jun 28 2004
STATUS
approved