A008300 Triangle read by rows: T(n,k) (n >= 0, 0 <= k <= n) gives number of {0,1} n X n matrices with all row and column sums equal to k.
1, 1, 1, 1, 2, 1, 1, 6, 6, 1, 1, 24, 90, 24, 1, 1, 120, 2040, 2040, 120, 1, 1, 720, 67950, 297200, 67950, 720, 1, 1, 5040, 3110940, 68938800, 68938800, 3110940, 5040, 1, 1, 40320, 187530840, 24046189440, 116963796250, 24046189440, 187530840, 40320, 1, 1, 362880, 14398171200, 12025780892160, 315031400802720, 315031400802720, 12025780892160, 14398171200, 362880, 1
Offset: 0
Examples
Triangle begins: 1; 1, 1; 1, 2, 1; 1, 6, 6, 1; 1, 24, 90, 24, 1; 1, 120, 2040, 2040, 120, 1; 1, 720, 67950, 297200, 67950, 720, 1; 1, 5040, 3110940, 68938800, 68938800, 3110940, 5040, 1; ...
References
- L. Comtet, Advanced Combinatorics, Reidel, 1974, p. 236, P(n,k).
Links
- Brendan D. McKay, Rows n = 0..30, flattened
- C. J. Everett and P. R. Stein, The asymptotic number of integer stochastic matrices, Disc. Math. 1 (1971), 55-72.
- Richard J. Mathar, 2-regular Digraphs of the Lovelock Lagrangian, arXiv:1903.12477 [math.GM], 2019.
- Richard J. Mathar, Rencontres for equipartite distributions of multisets of colored balls into urns, vixra:2306.0157 (2023)
- B. D. McKay, Applications of a technique for labeled enumeration, Congress. Numerantium, 40 (1983), 207-221.
- Brendan D. McKay, first 30 rows : entries named Bv[n,k,n,k]
- Wouter Meeussen, relevant entries from B. D. McKay reference
Crossrefs
Row sums give A067209.
Central coefficients are A058527.
Programs
-
PARI
T(n, k)={ local(M=Map(Mat([n, 1]))); my(acc(p, v)=my(z); mapput(M, p, if(mapisdefined(M, p, &z), z+v, v))); my(recurse(i, p, v, e) = if(i<0, if(!e, acc(p, v)), my(t=polcoef(p,i)); for(j=0, min(t, e), self()(i-1, p+j*(x-1)*x^i, binomial(t, j)*v, e-j)))); for(r=1, n, my(src=Mat(M)); M=Map(); for(i=1, matsize(src)[1], recurse(k-1, src[i, 1], src[i, 2], k))); vecsum(Mat(M)[,2]); } \\ Andrew Howroyd, Apr 03 2020
Formula
Comtet quotes Everett and Stein as showing that T(n,k) ~ (kn)!(k!)^(-2n) exp( -(k-1)^2/2 ) for fixed k as n -> oo.
T(n,k) = T(n,n-k).
Extensions
More terms from Greg Kuperberg, Feb 08 2001
Comments