OFFSET
0,3
COMMENTS
Length of row n = 2n+1. Rows have been reversed.
LINKS
D. Merlini, R. Sprugnoli and M. C. Verri, The tennis ball problem, J. Combin. Theory, A 99 (2002), 307-344 (Table A.1).
EXAMPLE
Triangle starts:
1;
1, 2, 3;
1, 4, 10, 16, 22;
1, 6, 21, 52, 105, 158, 211;
...
PROG
(PARI) T(n, k)=if(k<0 || k>2*n, 0, if(n<1, k==0, sum(j=0, k, (j+1)*T(n-1, k-j))))
CROSSREFS
KEYWORD
tabf,nonn
AUTHOR
N. J. A. Sloane, Jan 20 2003
STATUS
approved