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Denominators of even-numbered Maclaurin coefficients of sqrt(tan(x)/x).
2

%I #11 Nov 22 2023 22:22:53

%S 1,6,360,3024,1814400,887040,72648576000,784604620800,13857951744000,

%T 196503623737344000,8430005458332057600000,1249560422395084800000,

%U 747275354440475148288000000,25197383852207757066240000,2105181427080881417748480000000,154617478967448121358942208000000

%N Denominators of even-numbered Maclaurin coefficients of sqrt(tan(x)/x).

%C Denominators of Maclaurin coefficients of sqrt(tan(sqrt(x))/x^(1/4).

%H Robert Israel, <a href="/A367519/b367519.txt">Table of n, a(n) for n = 0..224</a>

%F sqrt(tan(x)/x) = Sum_{k=0..oo} A367518(k)/a(k) * x^(2*k).

%e sqrt(tan(x)/x) = 1 + (1/6) * x^2 + (19/360) * x^4 + (55/3024) * x^6 + ...

%p S:= series(sqrt(tan(x)/x), x, 41):

%p seq(denom(coeff(S,x,i)),i=0..40,2);

%Y Cf. A036279, A367518.

%K nonn,frac

%O 0,2

%A _Robert Israel_, Nov 21 2023