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%I #39 Sep 08 2022 08:44:38
%S 4,256,16384,1048576,67108864,4294967296,274877906944,17592186044416,
%T 1125899906842624,72057594037927936,4611686018427387904,
%U 295147905179352825856,18889465931478580854784,1208925819614629174706176
%N a(n) = 4^(3*n+1).
%C Additive digital root of a(n) = 4. - _Miquel Cerda_, Jul 02 2016
%H Vincenzo Librandi, <a href="/A013734/b013734.txt">Table of n, a(n) for n = 0..160</a>
%H Tanya Khovanova, <a href="http://www.tanyakhovanova.com/RecursiveSequences/RecursiveSequences.html">Recursive Sequences</a>
%H <a href="/index/Rec#order_01">Index entries for linear recurrences with constant coefficients</a>, signature (64).
%F a(n) = 64*a(n-1), n>0 ; a(0)=4. G.f.: 4/(1-64*x). a(n)=4*A089357(n). - _Philippe Deléham_, Nov 24 2008
%F E.g.f.: 4*exp(64*x). - _Ilya Gutkovskiy_, Jul 02 2016
%p seq(4^(3*n+1),n=0..13); # _Nathaniel Johnston_, Jun 26 2011
%t 4^(3*Range[0,20]+1) (* or *) NestList[64#&,4,20] (* _Harvey P. Dale_, Feb 22 2016 *)
%o (Magma) [4^(3*n+1): n in [0..20]]; // _Vincenzo Librandi_, May 25 2011
%o (PARI) Vec(4/(1-64*x) + O(x^99)) \\ _Altug Alkan_, Jul 05 2016
%o (PARI) a(n)=2^(6*n+2) \\ _Charles R Greathouse IV_, Jul 11 2016
%Y Cf. A013735.
%K nonn,easy
%O 0,1
%A _N. J. A. Sloane_.