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A153647
a(n) = 3^n*(n + 2)!.
2
2, 18, 216, 3240, 58320, 1224720, 29393280, 793618560, 23808556800, 785682374400, 28284565478400, 1103098053657600, 46330118253619200, 2084855321412864000, 100073055427817472000, 5103725826818691072000, 275601194648209317888000
OFFSET
0,1
LINKS
FORMULA
From G. C. Greubel, Mar 03 2021: (Start)
a(n) = 2*A051606(n).
G.f.: 2*Hypergeometric2F0([1, 3]; --; 3*x).
E.g.f.: 2/(1-3*x)^3. (End)
D-finite with recurrence a(n) +3*(-n-2)*a(n-1)=0. - R. J. Mathar, Aug 20 2021
MAPLE
A153647:= n-> 3^n*(n+2)!; seq(A153647(n), n=0..20); # G. C. Greubel, Mar 03 2021
MATHEMATICA
Table[3^n*(n + 2)!, {n, 0, 30}]
PROG
(Magma) [3^n*Factorial(n + 2): n in [0..20]]; // Vincenzo Librandi, Aug 24 2016
(Sage) [3^n*factorial(n+2) for n in (0..20)] # G. C. Greubel, Mar 03 2021
(PARI) a(n) = 3^n*(n + 2)!; \\ Michel Marcus, Mar 03 2021
CROSSREFS
Cf. A051606.
Sequence in context: A123855 A121407 A369027 * A052726 A217239 A279045
KEYWORD
nonn,easy
AUTHOR
STATUS
approved