OFFSET
0,8
COMMENTS
LINKS
Alois P. Heinz, Rows n = 0..100, flattened
Wikipedia, Young tableau
EXAMPLE
A(4,2) = 3:
+---------+ +---------+ +---------+
| 1 2 3 | | 1 2 4 | | 1 3 4 |
| 4 .-----+ | 3 .-----+ | 2 .-----+
+---+ +---+ +---+
Triangle T(n,k) begins:
1;
0, 1;
0, 1;
0, 1, 2;
0, 1, 3;
0, 1, 9;
0, 1, 14, 16;
0, 1, 34, 35;
0, 1, 55, 134;
0, 1, 125, 435;
0, 1, 209, 1213, 768;
0, 1, 461, 3454, 2310;
0, 1, 791, 10484, 11407;
...
MAPLE
h:= proc(l) local n; n:=nops(l); add(i, i=l)!/mul(mul(1+l[i]-j+
add(`if`(l[k]>=j, 1, 0), k=i+1..n), j=1..l[i]), i=1..n)
end:
g:= proc(n, i, k, l) `if`(n=0, h(l), `if`(n>k*(i-(k-1)/2), 0,
g(n, i-1, min(k, i-1), l)+`if`(i>n, 0, g(n-i, i-1, k-1, [l[], i]))))
end:
A:= proc(n, k) option remember; `if`(k<0, 0, g(n, n, k, [])) end:
T:= (n, k)-> A(n, k) -A(n, k-1):
seq(seq(T(n, k), k=0..floor((sqrt(1+8*n)-1)/2)), n=0..20);
MATHEMATICA
h[l_] := With[{n = Length[l]}, Sum[i, {i, l}]!/Product[Product[1+l[[i]] - j + Sum[If[l[[k]] >= j, 1, 0], {k, i+1, n}], {j, 1, l[[i]]}], {i, 1, n}] ];
g[n_, i_, k_, l_] := If[n == 0, h[l], If[n > k*(i-(k-1)/2), 0, g[n, i-1, Min[k, i-1], l] + If[i > n, 0, g[n-i, i-1, k-1, Append[l, i]]]]];
a[n_, k_] := a[n, k] = If[k < 0, 0, g[n, n, k, {}]];
t[n_, k_] := a[n, k] - a[n, k-1];
Table[Table[t[n, k], {k, 0, Floor[(Sqrt[1+8*n]-1)/2]}], {n, 0, 20}] // Flatten (* Jean-François Alcover, Dec 17 2013, translated from Maple *)
CROSSREFS
KEYWORD
nonn,tabf
AUTHOR
Alois P. Heinz, Nov 17 2012
STATUS
approved