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%I #17 Sep 08 2022 08:45:40
%S 2,18,216,3240,58320,1224720,29393280,793618560,23808556800,
%T 785682374400,28284565478400,1103098053657600,46330118253619200,
%U 2084855321412864000,100073055427817472000,5103725826818691072000,275601194648209317888000
%N a(n) = 3^n*(n + 2)!.
%H G. C. Greubel, <a href="/A153647/b153647.txt">Table of n, a(n) for n = 0..300</a>
%F From _G. C. Greubel_, Mar 03 2021: (Start)
%F a(n) = 2*A051606(n).
%F G.f.: 2*Hypergeometric2F0([1, 3]; --; 3*x).
%F E.g.f.: 2/(1-3*x)^3. (End)
%F D-finite with recurrence a(n) +3*(-n-2)*a(n-1)=0. - _R. J. Mathar_, Aug 20 2021
%p A153647:= n-> 3^n*(n+2)!; seq(A153647(n), n=0..20); # _G. C. Greubel_, Mar 03 2021
%t Table[3^n*(n + 2)!, {n, 0, 30}]
%o (Magma) [3^n*Factorial(n + 2): n in [0..20]]; // _Vincenzo Librandi_, Aug 24 2016
%o (Sage) [3^n*factorial(n+2) for n in (0..20)] # _G. C. Greubel_, Mar 03 2021
%o (PARI) a(n) = 3^n*(n + 2)!; \\ _Michel Marcus_, Mar 03 2021
%Y Cf. A051606.
%K nonn,easy
%O 0,1
%A _Roger L. Bagula_ and _Gary W. Adamson_, Dec 30 2008
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