OFFSET
0,3
MATHEMATICA
Table[Sum[Sum[Binomial[n-i, i+j]Binomial[n-j, i+j], {j, 0, n}], {i, 0, n}], {n, 0, 30}] (* Harvey P. Dale, Jan 25 2023 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Ralf Stephan, Oct 28 2004
STATUS
approved