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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
1, 2, 14, 200, 3536, 67472, 1423168, 34048352, 927156224, 28490354432, 976839578624, 36983803914752, 1532587515049984, 68997562105014272, 3353462146559209472, 175003916852177604608, 9760034505494167420928, 579311442062239341412352, 36462558160899681920745472, 2425761875540844266778656768 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

LINKS

Joerg Arndt, Table of n, a(n) for n = 0..100

Hyeong-Kwan Ju, Seunghyun Seo, Enumeration of 0/1-matrices avoiding some 2x2 matrices, arXiv:1107.1299 [math.CO], 2011.

H.-K. Ju and S. Seo, Enumeration of (0,1)-matrices avoiding some 2 X 2 matrices, Discrete Math., 312 (2012), 2473-2481.

FORMULA

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

MATHEMATICA

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-Fran├žois Alcover, Jul 22 2018, after Joerg Arndt *)

PROG

(PARI)

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

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

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

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

Vec(serlaplace(egf))

/* Joerg Arndt, Jul 19 2012 */

CROSSREFS

Cf. A048163, A014235.

Sequence in context: A263766 A244577 A090300 * A322196 A102224 A123543

Adjacent sequences:  A213974 A213975 A213976 * A213978 A213979 A213980

KEYWORD

nonn

AUTHOR

N. J. A. Sloane, Jul 05 2012

EXTENSIONS

More terms from Joerg Arndt, Jul 19 2012

STATUS

approved

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Last modified January 22 19:16 EST 2020. Contains 331153 sequences. (Running on oeis4.)