Consider f(n):= the number of ways of walking from the origin to the point,

    [53, 141],  in the QUARTER-PLANE, with 3*n-2 steps using the Kreweras steps {\
    [-1,0],[0,-1],[1,1]}

Then f(n)=0 for n<, 77, and defining, g(n) = f(n + 76),

    g(n)  is annihilated by an operator of order, 4,

    and degree in n of the  coefficients, 11



                                   Here it is



5832*(3*n+235)*(3*n+232)*(3*n+229)*(n+78)*(n+77)*(n+76)*(3*n+233)*(3*n+230)*(3*
n+227)*(21*n^2+34143*n+2952358)/(n+145)/(n+144)/(n+91)/(n+90)/(2*n+5)/(2*n+289)
/(2*n+181)/(n+3)/(n+2)/(21*n^2+34101*n+2918236)-108*(n+77)*(3*n+233)*(3*n+230)*
(3*n+235)*(3*n+232)*(n+78)*(1512*n^5+2809647*n^4+805762893*n^3+84510835761*n^2+
3328727049619*n+27050689091720)/(n+145)/(n+144)/(n+91)/(n+90)/(2*n+5)/(2*n+289)
/(2*n+181)/(n+3)/(n+2)/(21*n^2+34101*n+2918236)*N+18*(3*n+235)*(n+78)*(3*n+233)
*(4536*n^8+9496602*n^7+4469211495*n^6+947153820753*n^5+106321687256694*n^4+
6476731195774903*n^3+197934278641773205*n^2+2312706265341289192*n+
3067010931486129600)/(n+145)/(n+144)/(n+91)/(n+90)/(2*n+5)/(2*n+289)/(2*n+181)/
(n+3)/(n+2)/(21*n^2+34101*n+2918236)*N^2-3*(6048*n^8+12676500*n^7+5997897612*n^
6+1291074581475*n^5+149589090396207*n^4+9652910051766415*n^3+327298931391494013
*n^2+4671309917697977270*n+8143753488675040740)/(n+145)/(2*n+181)/(2*n+5)/(2*n+
289)/(n+91)/(n+3)/(21*n^2+34101*n+2918236)*N^3+N^4


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                         This took, 211.273, seconds.