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a(n) = 2^(2^(n-1) + n - 2).
3

%I #19 Sep 08 2022 08:44:50

%S 1,4,32,1024,524288,68719476736,590295810358705651712,

%T 21778071482940061661655974875633165533184,

%U 14821387422376473014217086081112052205218558037201992197050570753012880593911808

%N a(n) = 2^(2^(n-1) + n - 2).

%H Vincenzo Librandi, <a href="/A028369/b028369.txt">Table of n, a(n) for n = 1..12</a>

%F a(n) = 2^A052944(n-1). - _R. J. Mathar_, Dec 15 2015

%t Table[2^(2^(n-1)+n-2),{n,10}] (* _Harvey P. Dale_, Aug 20 2019 *)

%o (Magma) [2^(n-1)*2^(2^(n-1)-1): n in [1..10]]; // _Vincenzo Librandi_, Jun 03 2011

%o (PARI) a(n)=1<<(2^(n-1)+n-2) \\ _Charles R Greathouse IV_, Jun 05 2011

%K nonn,easy

%O 1,2

%A _N. J. A. Sloane_

%E One more term (a(9)) from _Harvey P. Dale_, Aug 20 2019