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A213977 Number of n X n matrices with entries 0 and 1 and no 2 X 2 submatrix of form [ 1 1; 0 0 ]. 2

%I #24 Jul 22 2018 10:42:33

%S 1,2,14,200,3536,67472,1423168,34048352,927156224,28490354432,

%T 976839578624,36983803914752,1532587515049984,68997562105014272,

%U 3353462146559209472,175003916852177604608,9760034505494167420928,579311442062239341412352,36462558160899681920745472,2425761875540844266778656768

%N Number of n X n matrices with entries 0 and 1 and no 2 X 2 submatrix of form [ 1 1; 0 0 ].

%H Joerg Arndt, <a href="/A213977/b213977.txt">Table of n, a(n) for n = 0..100</a>

%H Hyeong-Kwan Ju, Seunghyun Seo, <a href="http://arxiv.org/abs/1107.1299">Enumeration of 0/1-matrices avoiding some 2x2 matrices</a>, arXiv:1107.1299 [math.CO], 2011.

%H H.-K. Ju and S. Seo, <a href="https://doi.org/10.1016/j.disc.2012.04.019">Enumeration of (0,1)-matrices avoiding some 2 X 2 matrices</a>, Discrete Math., 312 (2012), 2473-2481.

%F Ju and Seo give an e.g.f. (see PARI code).

%t terms = 20; w = ProductLog[-x E^x]; CoefficientList[-2w/(x(w+1)) + (x^2-1) E^(2x) - 2x(x+1) E^(4x) + O[x]^terms, x]*Range[0, terms-1]! (* _Jean-François Alcover_, Jul 22 2018, after _Joerg Arndt_ *)

%o (PARI)

%o N=66; x='x+O('x^N);

%o W(x)=sum(n=1,N, (-n)^(n-1)*x^n/n! );

%o w=W(-x*exp(x));

%o egf=-2*w/(x*(1+w)) + (x^2-1)*exp(2*x)-2*x*(x+1)*exp(4*x);

%o Vec(serlaplace(egf))

%o /* _Joerg Arndt_, Jul 19 2012 */

%Y Cf. A048163, A014235.

%K nonn

%O 0,2

%A _N. J. A. Sloane_, Jul 05 2012

%E More terms from _Joerg Arndt_, Jul 19 2012

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Last modified March 29 04:59 EDT 2024. Contains 371264 sequences. (Running on oeis4.)