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a(n) = (3*n)^n.
4

%I #26 Sep 08 2022 08:45:12

%S 1,3,36,729,20736,759375,34012224,1801088541,110075314176,

%T 7625597484987,590490000000000,50542106513726817,4738381338321616896,

%U 482880748567480579719,53148384174432398229504,6283298708943145751953125,794071845499378503449051136

%N a(n) = (3*n)^n.

%F E.g.f.: 1/(1 + LambertW(-3*x)). - _Ilya Gutkovskiy_, Oct 03 2017

%t Join[{1}, Table[(3 n)^n, {n, 20}]] (* _Vincenzo Librandi_, Jun 21 2015 *)

%o (Magma) [(3*n)^n : n in [0..20]]; // _Zaki Khandaker_, Jun 21 2015

%o (PARI) a(n) = (3*n)^n \\ _Charles R Greathouse IV_, Jun 21 2015

%Y Cf. A062971, A091483.

%K nonn,easy

%O 0,2

%A _Christian G. Bower_, Jan 13 2004