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A287047 a(n) is the number of rooted maps with n edges and 7 faces on an orientable surface of genus 1. 9

%I

%S 60060,3944928,129726760,2908358552,50534154408,729734918432,

%T 9145847808784,102432266545800,1046677747672360,9908748651241088,

%U 87930943305742512,738178726378902064,5905479331377981200,45289976937922983360,334600965220354244896,2391127223524518889064,16585285393291515557928

%N a(n) is the number of rooted maps with n edges and 7 faces on an orientable surface of genus 1.

%H Sean R. Carrell, Guillaume Chapuy, <a href="http://arxiv.org/abs/1402.6300">Simple recurrence formulas to count maps on orientable surfaces</a>, arXiv:1402.6300 [math.CO], 2014.

%t Q[0, 1, 0] = 1; Q[n_, f_, g_] /; n < 0 || f < 0 || g < 0 = 0;

%t 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}]);

%t a[n_] := Q[n, 7, 1];

%t Table[a[n], {n, 8, 24}] (* _Jean-Fran├žois Alcover_, Oct 18 2018 *)

%o (PARI)

%o A000108_ser(N) = my(x='x+O('x^(N+1))); (1 - sqrt(1-4*x))/(2*x);

%o A287047_ser(N) = {

%o my(y = A000108_ser(N+1));

%o -4*y*(y-1)^8*(184142*y^7 + 1083793*y^6 - 1540136*y^5 - 1481152*y^4 + 2626176*y^3 - 737232*y^2 - 184896*y + 64320)/(y-2)^23;

%o };

%o Vec(A287047_ser(17))

%Y Rooted maps of genus 1 with n edges and f faces for 1<=f<=10: A002802(with offset 2) f=1, A006295 f=2, A006296 f=3, A288071 f=4, A288072 f=5, A287046 f=6, this sequence, A287048 f=8, A288073 f=9, A288074 f=10.

%Y Column 7 of A269921, column 1 of A270411.

%Y Cf. A000108.

%K nonn

%O 8,1

%A _Gheorghe Coserea_, Jun 04 2017

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Last modified April 1 04:15 EDT 2020. Contains 333155 sequences. (Running on oeis4.)