%I #7 Sep 04 2020 10:07:16
%S 0,1,8,102,2448,99576,6070032,517803840,58901955840,8614609282944,
%T 1574889814326528,351896788824053760,94354291010501932032,
%U 29899137879209196380160,11053567519385396409446400,4715135497874174650128617472,2298676381054790419739595571200,1270045124912998373344157769891840
%N a(0) = 0; a(n) = 6^(n-1) + (1/n) * Sum_{k=1..n-1} binomial(n,k)^2 * 6^(k-1) * (n-k) * a(n-k).
%F Sum_{n>=0} a(n) * x^n / (n!)^2 = -log((7 - BesselI(0,2*sqrt(6*x))) / 6).
%t a[0] = 0; a[n_] := a[n] = 6^(n - 1) + (1/n) Sum[Binomial[n, k]^2 6^(k - 1) (n - k) a[n - k], {k, 1, n - 1}]; Table[a[n],{n, 0, 17}]
%t nmax = 17; CoefficientList[Series[-Log[(7 - BesselI[0, 2 Sqrt[6 x]])/6], {x, 0, nmax}], x] Range[0, nmax]!^2
%Y Cf. A102223, A333981, A333982, A333983, A333984, A337597.
%K nonn
%O 0,3
%A _Ilya Gutkovskiy_, Sep 04 2020
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