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A278179 a(n) is the denominator of intersection number , n>=2.

%I A278179 #19 Nov 24 2016 09:33:05
%S A278179 240,144,48,8,96,1,32,1,32,1,8,1,16,1,64,1,32,1,32,1,64,1,16,1,16,1,8,
%T A278179 1,16,1,128,1,32,1,32,1,64,1,64,1,64,1,4,1,8,1,32,1,16,1,16,1,32,1,16,
%U A278179 1,16,1,8,1,16,1,256,1,32,1,32,1,64,1,64,1,64,1,16,1,32,1,128,1,64,1,64,1,128
%N A278179 a(n) is the denominator of intersection number <tau_2^(3n-3)>, n>=2.
%C A278179 For 'intersection numbers' see Section 1 in Itzykson and Zuber paper.
%H A278179 Gheorghe Coserea, <a href="/A278179/b278179.txt">Table of n, a(n) for n = 2..1025</a>
%H A278179 Stavros Garoufalidis, Marcos Marino, <a href="https://arxiv.org/abs/0812.1195v4">Universality and asymptotics of graph counting problems in nonorientable surfaces</a>, arXiv:0812.1195 [math.CO], 2008.
%H A278179 C. Itzykson, J.-B. Zuber, <a href="https://arxiv.org/abs/hep-th/9201001">Combinatorics of the Modular Group II: the Kontsevich integrals</a>, arXiv:hep-th/9201001, 1991.
%F A278179 a(n) = denominator((3*n-3)!*4^n/((5*n-5)*(5*n-3)) * A269418(n)/A269419(n)) for n >= 2.
%e A278179 7/240, 1225/144, 1816871/48, 7723802625/8, 8591613499103635/96, ...
%o A278179 (PARI)
%o A278179 A269418_seq(N) = {
%o A278179   my(y  = vector(N)); y[1] = 1/48;
%o A278179   for (n = 2, N,
%o A278179        y[n] = (25*(n-1)^2-1)/48 * y[n-1] + 1/2*sum(k = 1, n-1, y[k]*y[n-k]));
%o A278179   concat(-1, y);
%o A278179 };
%o A278179 seq(N) = {
%o A278179   my(y = A269418_seq(N+2));
%o A278179   vector(N, g, (3*g)! * 4^(g+1) / ((5*g)*(5*g+2)) * y[g+2]);
%o A278179 };
%o A278179 apply(denominator, seq(85))
%Y A278179 Cf. A269418, A269419, A278178 (numerator).
%K A278179 nonn,frac
%O A278179 2,1
%A A278179 _Gheorghe Coserea_, Nov 13 2016