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%I #17 Apr 17 2013 15:58:50
%S 1,1,5,15,62,233,937,3729,15121,61492,251942,1036215,4279754,17731181,
%T 73670725,306823695,1280574706,5354602495,22426876445,94070238840,
%U 395106054632,1661489413472,6994494531010,29474635716345,124319047552309,524797934104312,2217091297558466,9373180869094923
%N Number of lattice paths from (0,0) to (n,n) using steps (1,0), (1,1), (0,2), (2,2).
%F G.f.: A(x) where (4*x^6+12*x^5-20*x^3+27*x^2+12*x-4)*A(x)^3-(3*x^2+3*x-3)*A(x)+1 = 0. - _Mark van Hoeij_, Apr 17 2013
%p P := (4*x^6+12*x^5-20*x^3+27*x^2+12*x-4)*A^3-(3*x^2+3*x-3)*A+1;
%p Q := eval(P, A=A+1):
%p series(RootOf(Q,A)+1, x=0, 30); # _Mark van Hoeij_, Apr 17 2013
%o (PARI) /* same as in A092566 but use */
%o steps=[[1,0], [1,1], [0,2], [2,2]];
%o /* Joerg Arndt, Jun 30 2011 */
%Y Cf. A001850, A026641, A036355, A137644, A192364, A192365, A192369, A191354.
%K nonn
%O 0,3
%A _Joerg Arndt_, Jun 30 2011
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