%I
%S 1,1,0,1,4,0,16,0,4,36,0,324,0,324,0,36,576,0,9216,0,20736,0,9216,0,
%T 576,14400,0,360000,0,1440000,0,1440000,0,360000,0,14400,518400,0,
%U 18662400,0,116640000,0,207360000,0,116640000
%N Cardmatching numbers (DinnerDiner matching numbers).
%C This is a triangle of card matching numbers. Two decks each have 2 kinds of cards, n of each kind. The first deck is laid out in order. The second deck is shuffled and laid out next to the first. A match occurs if a card from the second deck is next to a card of the same kind from the first deck. Triangle T(n,k) is the number of ways of achieving exactly k matches (k=0..2n). The probability of exactly k matches is T(n,k)/(2n)!.
%C rows are of length 1,3,5,7,...
%D F. N. David and D. E. Barton, Combinatorial Chance, Hafner, NY, 1962, Ch. 7 and Ch. 12.
%D J. Riordan, An Introduction to Combinatorial Analysis, Wiley, 1958, pp. 174178.
%D R. P. Stanley, Enumerative Combinatorics Volume I, Cambridge University Press, 1997, p. 71.
%H F. F. Knudsen and I. Skau, <a href="http://www.jstor.org/stable/2691467">On the Asymptotic Solution of a CardMatching Problem</a>, Mathematics Magazine 69 (1996), 190197.
%H Barbara H. Margolius, <a href="http://academic.csuohio.edu/bmargolius/homepage/dinner/dinner/cardentry.htm">DinnerDiner Matching Probabilities</a>
%H B. H. Margolius, <a href="http://www.jstor.org/stable/3219303">The DinnerDiner Matching Problem</a>, Mathematics Magazine, 76 (2003), 107118.
%H S. G. Penrice, <a href="http://www.jstor.org/stable/2324927">Derangements, permanents and Christmas presents</a>, The American Mathematical Monthly 98(1991), 617620.
%H <a href="/index/Ca#cardmatch">Index entries for sequences related to card matching</a>
%F G.f.: sum(coeff(R(x, n, k), x, j)*(t1)^j*(n*kj)!, j=0..n*k) where n is the number of kinds of cards (2 in this case), k is the number of cards of each kind and R(x, n, k) is the rook polynomial given by R(x, n, k)=(k!^2*sum(x^j/((kj)!^2*j!))^n (see Stanley or Riordan). coeff(R(x, n, k), x, j) indicates the of coefficient x^j of the rook polynomial.
%e There are 16 ways of matching exactly 2 cards when there are 2 cards of each kind and 2 kinds of card so T(2,2)=16.
%p p := (x,k)>k!^2*sum(x^j/((kj)!^2*j!),j=0..k); R := (x,n,k)>p(x,k)^n; f := (t,n,k)>sum(coeff(R(x,n,k),x,j)*(t1)^j*(n*kj)!,j=0..n*k);
%p for n from 0 to 7 do seq(coeff(f(t,2,n),t,m),m=0..2*n); od;
%t p[x_, k_] := k!^2*Sum[ x^j/((kj)!^2*j!), {j, 0, k}];
%t f[t_, n_, k_] := Sum[ Coefficient[ p[x, k]^n, x, j]*(t1)^j*(n*kj)!, {j, 0, n*k}]; Table[ Coefficient[ f[t, 2, n], t, m], {n, 0, 7}, {m, 0, 2*n}] // Flatten (* _JeanFrançois Alcover_, Sep 17 2012, translated from Maple *)
%Y Cf. A008290, A059056A059071.
%K nonn,tabf,nice
%O 0,5
%A Barbara Haas Margolius (margolius(AT)math.csuohio.edu)
