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A204321 Start with 4. Square the previous term and subtract it.

%I A204321 #28 Jun 20 2023 12:12:45
%S A204321 4,12,132,17292,298995972,89398590973228812,
%T A204321 7992108067998667938125889533702532,
%U A204321 63873791370569400659097694858350356285036046451665934814399129508492
%N A204321 Start with 4. Square the previous term and subtract it.
%H A204321 Vincenzo Librandi, <a href="/A204321/b204321.txt">Table of n, a(n) for n = 1..11</a>
%H A204321 J. A. Haddley, <a href="http://www.joelhaddley.co.uk/University/pdf/cuboids.pdf">Doubling Hypercuboids</a>, Preprint 2015.
%F A204321 a(n) = a(n-1)*(a(n-1)-1).
%F A204321 a(n) ~ c^(2^n), where c = 1.8401979467004699327247921093647566233474761412868967823409865843403604499... . - _Vaclav Kotesovec_, Dec 18 2014
%p A204321 A204321 := proc(n)
%p A204321         if n = 1 then
%p A204321                 4;
%p A204321         else
%p A204321                 procname(n-1)*(procname(n-1)-1) ;
%p A204321         end if;
%p A204321 end proc:
%p A204321 seq(A204321(n),n=1..10) ; # _R. J. Mathar_, Jan 19 2012
%t A204321 Join[{a = 4}, Table[a = a^2 - a, {n, 9}]] (* _Vladimir Joseph Stephan Orlovsky_, Feb 24 2012 *)
%t A204321 RecurrenceTable[{a[1]==4, a[n] == a[n-1]*(a[n-1]-1)}, a, {n, 1, 10}] (* _Vaclav Kotesovec_, Dec 18 2014 *)
%t A204321 NestList[#^2-#&,4,10] (* _Harvey P. Dale_, Jun 20 2023 *)
%K A204321 nonn
%O A204321 1,1
%A A204321 _Daniel Chiverton_, Jan 14 2012