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%I #8 Jul 20 2019 08:03:20
%S 1,3,19,223,4667,160045,8207125,587420875,55869454855,6809387511403,
%T 1034264079708019,191477762192490649,42435372869814513769,
%U 11090351278621719882899,3374951549996881393302715
%N Diagonal sums of exponential Riordan array [1+x^2*sec(x),x], A166378.
%F a(n) = Sum_{k=0..n} C(n+k,2k)*A166377(k).
%t (* The function RiordanArray is defined in A256893. *)
%t nmax = 14; R = RiordanArray[1 + #^2 Sec[#]&, #&, 2 nmax + 1, True];
%t a[n_] := Sum[R[[i, 2 n - i + 2]], {i, 2 n + 1, n + 1, -1}];
%t Table[a[n], {n, 0, nmax}] (* _Jean-François Alcover_, Jul 20 2019 *)
%Y Cf. A166377, A166378.
%K easy,nonn
%O 0,2
%A _Paul Barry_, Oct 13 2009
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