OFFSET
1,13
COMMENTS
Equivalently, T(k,n,h) is the number of ordered sets of n nonnegative integers < k with the sum equal to h.
From Juan Pablo Herrera P., Nov 21 2016: (Start)
T(k,n,h) is the number of possible ways of randomly selecting h cards from k-1 sets, each with n different playing cards. It is also the number of lattice paths from (0,0) to (n,h) using steps (1,0), (1,1), (1,2), ..., (1,k-1).
Shallow diagonal sums of each triangle with fixed k give the k-bonacci numbers. (End)
T(k,n,h) is the number of n-dimensional grid points of a k X k X ... X k grid, which are lying in the (n-1)-dimensional hyperplane which is at an L1 distance of h from one of the grid's corners, and normal to the corresponding main diagonal of the grid. - Eitan Y. Levine, Apr 23 2023
LINKS
Andrey Zabolotskiy, slices with k+n = 1..20, flattened
Florentin Smarandache, K-Nomial Coefficients, arXiv:math/0612062 [math.GM], 2006 (originally published in French in: F. Smarandache, Généralisations et Généralités, Ed. Nouvelle, 1984, pp. 24-26).
FORMULA
T(k,n,h) = Sum_{i = 0..floor(h/k)} (-1)^i*binomial(n,i)*binomial(n+h-1-k*i,n-1). [Corrected by Eitan Y. Levine, Apr 23 2023]
From Eitan Y. Levine, Apr 23 2023: (Start)
(T(k,n,h))_{h=0..n*(k-1)} = f(f(...f(g(P))...)), where:
(x_i)_{i=0..m} denotes a tuple (in particular, the LHS contains the values for 0 <= h <= n*(k-1)),
f repeats n times,
f((x_i)_{i=0..m}) = (Sum_{j=0..i} x_j)_{i=0..m} is the cumulative sum function,
g((x_i)_{i=0..m}) = (x_(i/k) if k|i, otherwise 0)_{i=0..m*k} is adding k-1 zeros between adjacent elements,
and P=((-1)^i*binomial(n,i))_{i=0..n} is the n-th row of Pascal's triangle, with alternating signs. (End)
From Eitan Y. Levine, Jul 27 2023: (Start)
Recurrence relations, the first follows from the sequence's defining polynomial as mentioned in the Smarandache link:
T(k,n+1,h) = Sum_{i = 0..s-1} T(k,n,h-i)
T(k+1,n,h) = Sum_{i = 0..n} binomial(n,i)*T(k,n-i,h-i*k) (End)
EXAMPLE
For first few k and for first few n, the rows with h = 0..n*(k-1) are given:
k=1: 1; 1; 1; 1; 1; ...
k=2: 1; 1, 1; 1, 2, 1; 1, 3, 3, 1; 1, 4, 6, 4, 1; ...
k=3: 1; 1, 1, 1; 1, 2, 3, 2, 1; 1, 3, 6, 7, 6, 3, 1; ...
k=4: 1; 1, 1, 1, 1; 1, 2, 3, 4, 3, 2, 1; ...
For example, (1 + x + x^2)^3 = 1 + 3*x + 6*x^2 + 7*x^3 + 6*x^4 + 3*x^5 + x^6, hence T(3,3,2) = T(3,3,4) = 6.
From Eitan Y. Levine, Apr 23 2023: (Start)
Example for the repeated cumulative sum formula, for (k,n)=(3,3) (each line is the cumulative sum of the previous line, and the first line is the padded, alternating 3rd row from Pascal's triangle):
1 0 0 -3 0 0 3 0 0 -1
1 1 1 -2 -2 -2 1 1 1
1 2 3 1 -1 -3 -2 -1
1 3 6 7 6 3 1
which is T(3,3,h). (End)
MATHEMATICA
a = Table[CoefficientList[Sum[x^(h-1), {h, k}]^n, x], {k, 10}, {n, 0, 9}];
Flatten@Table[a[[s-n, n+1]], {s, 10}, {n, 0, s-1}]
(* alternate program *)
row[k_, n_] := Nest[Accumulate, Upsample[Table[((-1)^j)*Binomial[n, j], {j, 0, n}], k], n][[;; n*(k-1)+1]] (* Eitan Y. Levine, Apr 23 2023 *)
CROSSREFS
k-nomial arrays for fixed k=1..10: A000012, A007318, A027907, A008287, A035343, A063260, A063265, A171890, A213652, A213651.
Central n-nomial coefficients for n=1..9, i.e., sequences with h=floor(n*(k-1)/2) and fixed n: A000012, A000984 (A001405), A002426, A005721 (A005190), A005191, A063419 (A018901), A025012, (A025013), A025014, A174061 (A025015), A201549, (A225779), A201550. Arrays: A201552, A077042, see also cfs. therein.
KEYWORD
nonn,tabf,easy
AUTHOR
Andrey Zabolotskiy, Nov 10 2016
STATUS
approved