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Number of column convex polyominoes with n hexagonal cells.
10

%I #28 Jul 23 2020 19:19:45

%S 1,3,11,42,162,626,2419,9346,36106,139483,538841,2081612,8041537,

%T 31065506,120010109,463614741,1791004361,6918884013,26728553546,

%U 103255896932,398891029862,1540968200661,5952961630324,22997069087436

%N Number of column convex polyominoes with n hexagonal cells.

%H Michael De Vlieger, <a href="/A059716/b059716.txt">Table of n, a(n) for n = 1..1704</a>

%H Moa Apagodu, <a href="http://arXiv.org/abs/math.CO/0202295">Counting hexagonal lattice animals</a>, arXiv:math/0202295 [math.CO], 2002-2009.

%H M. Bousquet-Mélou and A. Rechnitzer, <a href="http://www.labri.fr/Perso/~bousquet/Articles/Klarner/article.ps.gz">Lattice animals and heaps of dimers</a>

%H D. A. Klarner, <a href="http://dx.doi.org/10.4153/CJM-1967-080-4">Cell growth problems</a>, Canad. J. Math. 19 (1967) 851-863.

%H K. A. Van'kov, V. M. Zhuravlyov, <a href="https://www.mccme.ru/free-books/matpros/pdf/mp-22.pdf#page=127">Regular tilings and generating functions</a>, Mat. Pros. Ser. 3, issue 22, 2018 (127-157) [in Russian]. See page 128. - _N. J. A. Sloane_, Jan 09 2019

%H Kirill Vankov, Valerii Zhuravlev, <a href="https://hal.archives-ouvertes.fr/hal-02535947">Regular and semiregular (uniform) tilings and generating functions</a>, hal-02535947, [math.CO], 2020.

%H V. M. Zhuravlev, <a href="http://www.mccme.ru/free-books/matpros/mph.pdf">Horizontally-convex polyiamonds and their generating functions</a>, Mat. Pros. 17 (2013), 107-129 (in Russian).

%H <a href="/index/Rec#order_04">Index entries for linear recurrences with constant coefficients</a>, signature (6, -10, 7, -1).

%F G.f.: x(1-x)^3/(1-6x+10x^2-7x^3+x^4).

%p gf := x*(1-x)^3/(1-6*x+10*x^2-7*x^3+x^4): s := series(gf, x, 50): for i from 1 to 100 do printf(`%d,`,coeff(s,x,i)) od:

%t a[1]=1; a[2]=3; a[3]=11; a[4]=42; a[n_] := a[n] = 6*a[n-1] - 10*a[n-2] + 7*a[n-3] - a[n-4]; Table[a[n], {n, 1, 24}] (* _Jean-François Alcover_, Mar 30 2015 *)

%t LinearRecurrence[{6,-10,7,-1},{1,3,11,42},24] (* _Ray Chandler_, Jul 16 2015 *)

%K nonn

%O 1,2

%A _Mireille Bousquet-Mélou_, Feb 08 2001

%E More terms from _James A. Sellers_, Feb 09 2001