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Array read by ascending antidiagonals: the s-th column gives the central s-binomial coefficients.
3

%I #15 Feb 13 2024 19:38:20

%S 1,1,1,1,2,1,1,6,3,1,1,20,19,4,1,1,70,141,44,5,1,1,252,1107,580,85,6,

%T 1,1,924,8953,8092,1751,146,7,1,1,3432,73789,116304,38165,4332,231,8,

%U 1,1,12870,616227,1703636,856945,135954,9331,344,9,1,1,48620,5196627,25288120,19611175,4395456,398567,18152,489,10,1

%N Array read by ascending antidiagonals: the s-th column gives the central s-binomial coefficients.

%H William Linz, <a href="https://arxiv.org/abs/2110.12095">s-Catalan numbers and Littlewood-Richardson polynomials</a>, arXiv:2110.12095 [math.CO], 2021. See p. 2.

%F A(n, s) = T(2*n, s*n, s), where T(n, k, s) is the s-binomial coefficient defined as the coefficient of x^k in (Sum_{i=0..s} x^i)^n.

%e The array begins:

%e n\s | 0 1 2 3 4

%e ----+----------------------------

%e 0 | 1 1 1 1 1 ...

%e 1 | 1 2 3 4 5 ...

%e 2 | 1 6 19 44 85 ...

%e 3 | 1 20 141 580 1751 ...

%e 4 | 1 70 1107 8092 38165 ...

%e ...

%t T[n_,k_,s_]:=If[k==0,1,Coefficient[(Sum[x^i,{i,0,s}])^n,x^k]]; A[n_,s_]:=T[2n,s n,s]; Flatten[Table[A[n-s,s],{n,0,9},{s,0,n}]]

%Y Cf. A000984 (s=1), A082758 (s=2), A005721 (s=3), A349936 (s=4), A063419 (s=5), A270918 (n=s), A163269 (s>0).

%Y Cf. A007318, A008287, A025012, A027907, A035343, A063260.

%Y Cf. A349934, A349935.

%K nonn,easy,tabl

%O 0,5

%A _Stefano Spezia_, Dec 06 2021