A269925 Triangle read by rows: T(n,f) is the number of rooted maps with n edges and f faces on an orientable surface of genus 5.
59520825, 4304016990, 4304016990, 158959754226, 354949166565, 158959754226, 4034735959800, 14805457339920, 14805457339920, 4034735959800, 79553497760100, 420797306522502, 691650582088536, 420797306522502, 79553497760100, 1302772718028600, 9220982517965400, 21853758736216200, 21853758736216200, 9220982517965400, 1302772718028600
Offset: 10
Examples
Triangle starts: n\f [1] [2] [3] [4] [10] 59520825; [11] 4304016990, 4304016990; [12] 15895975422, 354949166565, 158959754226; [13] 4034735959800, 14805457339920, 14805457339920, 4034735959800; [14] ...
Links
- Gheorghe Coserea, Rows n = 10..210, flattened
- Sean R. Carrell, Guillaume Chapuy, Simple recurrence formulas to count maps on orientable surfaces, arXiv:1402.6300 [math.CO], 2014.
Crossrefs
Programs
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Mathematica
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)((2n-1)/3 Q[n-1, f, g] + (2n-1)/3 Q[n - 1, f-1, g] + (2n-3)(2n-2)(2n-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] (2k-1)(2l-1) Q[k-1, u, i] Q[l-1, v, j], {i, 0, g}], {u, 1, f}], {k, 1, n}]); Table[Q[n, f, 5], {n, 10, 15}, {f, 1, n-9}] // Flatten (* Jean-François Alcover, Aug 10 2018 *)
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PARI
N = 15; G = 5; gmax(n) = min(n\2, G); Q = matrix(N + 1, N + 1); Qget(n, g) = { if (g < 0 || g > n/2, 0, Q[n+1, g+1]) }; Qset(n, g, v) = { Q[n+1, g+1] = v }; Quadric({x=1}) = { Qset(0, 0, x); for (n = 1, length(Q)-1, for (g = 0, gmax(n), my(t1 = (1+x)*(2*n-1)/3 * Qget(n-1, g), t2 = (2*n-3)*(2*n-2)*(2*n-1)/12 * Qget(n-2, g-1), t3 = 1/2 * sum(k = 1, n-1, sum(i = 0, g, (2*k-1) * (2*(n-k)-1) * Qget(k-1, i) * Qget(n-k-1, g-i)))); Qset(n, g, (t1 + t2 + t3) * 6/(n+1)))); }; Quadric('x); concat(apply(p->Vecrev(p/'x), vector(N+1 - 2*G, n, Qget(n-1 + 2*G, G))))
Comments