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%I #8 Mar 23 2021 15:54:00
%S 3,16,60,384,1680,12288,60480,491520,2661120,23592960,138378240,
%T 1321205760,8302694400,84557168640,564583219200,6088116142080,
%U 42908324659200,487049291366400,3604299271372800,42860337640243200
%N a(n) = 2^n * (n + 3)!!.
%H G. C. Greubel, <a href="/A155160/b155160.txt">Table of n, a(n) for n = 0..500</a>
%F a(n) = 2^n*(n+3)!!.
%F From _G. C. Greubel_, Mar 19 2021: (Start)
%F a(2*n) = 2^(n-1)*(2*n+3)!/(n+1)!.
%F a(2*n+1) = 2^(4*n+3)*(n+2)!. (End)
%t Table[2^n*(n+3)!!, {n, 0, 30}]
%t Table[2^n*If[EvenQ[n], (n+3)!/(2^(n/2+1)*(n/2+1)!), 2^((n+3)/2)*((n+3)/2)!], {n, 0, 30}] (* _G. C. Greubel_, Mar 19 2021 *)
%o (Magma) [(n mod 2) eq 0 select Round(2^(n)*Factorial(n+3)/(2^(n/2+1)*Gamma((n+4)/2))) else Round(2^(n+(n+3)/2)*Gamma((n+5)/2)): n in [0..30]]; // _G. C. Greubel_, Mar 19 2021
%o (Sage) [2^n*(n+3).multifactorial(2) for n in (0..30)] # _G. C. Greubel_, Mar 19 2021
%Y Cf. A000079, A006882.
%K nonn
%O 0,1
%A _Roger L. Bagula_, Jan 21 2009
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