OFFSET
0,2
LINKS
Lars Blomberg, Table of n, a(n) for n = 0..5049 (The first 100 antidiagonals)
M. Dziemianczuk, Counting Lattice Paths With Four Types of Steps, Graphs and Combinatorics, September 2013, DOI 10.1007/s00373-013-1357-1.
EXAMPLE
Array begins:
1, 3, 15, 81, 459, 2673, 15849, ...
6, 33, 189, 1107, 6588, 39663, 240894, ...
60, 378, 2349, 14553, 90207, 560115, 3485187, ...
675, 4509, 29403, 189351, 1211031, 7715331, 49045662, ...
7992, 55188, 371358, 2458998, 16112925, 104838219, 678790125, ...
...
PROG
(PARI) \\ Dziemianczuk, Proposition 1
S(n, k)=sum(i=0, n+k, sum(j=0, i, binomial(k, j)*binomial(j, i-j)*binomial(2*k+n-i, k)));
A=[]; for(i=1, 10, A=concat(A, vector(i, j, S(j-1, i-1))));
A \\ Lars Blomberg, Jul 20 2017
CROSSREFS
KEYWORD
nonn,tabl
AUTHOR
N. J. A. Sloane, Dec 05 2013
EXTENSIONS
a(15)-a(38) from Lars Blomberg, Jul 20 2017
STATUS
approved