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A288071
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a(n) is the number of rooted maps with n edges and 4 faces on an orientable surface of genus 1.
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9
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420, 14065, 256116, 3392843, 36703824, 344468530, 2908358552, 22620890127, 164767964504, 1137369687454, 7506901051000, 47700234551918, 293370096957504, 1753945289216484, 10229201477344752, 58364244137596695, 326571194881454376, 1795631576981016038, 9718877491130813368, 51858415558095569962
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OFFSET
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5,1
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LINKS
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MATHEMATICA
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Q[0, 1, 0] = 1; Q[n_, f_, g_] /; n < 0 || f < 0 || g < 0 = 0;
Q[n_, f_, g_] := Q[n, f, g] = 6/(n + 1) ((2 n - 1)/3 Q[n - 1, f, g] + (2 n - 1)/3 Q[n - 1, f - 1, g] + (2 n - 3) (2 n - 2) (2 n - 1)/12 Q[n - 2, f, g - 1] + 1/2 Sum[l = n - k; Sum[v = f - u; Sum[j = g - i; Boole[l >= 1 && v >= 1 && j >= 0] (2 k - 1) (2 l - 1) Q[k - 1, u, i] Q[l - 1, v, j], {i, 0, g}], {u, 1, f}], {k, 1, n}]);
a[n_] := Q[n, 4, 1];
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PROG
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(PARI)
A000108_ser(N) = my(x='x+O('x^(N+1))); (1 - sqrt(1-4*x))/(2*x);
y*(y-1)^5*(307*y^4 + 2411*y^3 - 2094*y^2 - 708*y + 504)/(y-2)^14;
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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