A204321 - OEIS

%I #28 Jun 20 2023 12:12:45

%S 4,12,132,17292,298995972,89398590973228812,

%T 7992108067998667938125889533702532,

%U 63873791370569400659097694858350356285036046451665934814399129508492

%N Start with 4. Square the previous term and subtract it.

%H Vincenzo Librandi, <a href="/A204321/b204321.txt">Table of n, a(n) for n = 1..11</a>

%H J. A. Haddley, <a href="http://www.joelhaddley.co.uk/University/pdf/cuboids.pdf">Doubling Hypercuboids</a>, Preprint 2015.

%F a(n) = a(n-1)*(a(n-1)-1).

%F a(n) ~ c^(2^n), where c = 1.8401979467004699327247921093647566233474761412868967823409865843403604499... . - _Vaclav Kotesovec_, Dec 18 2014

%p A204321 := proc(n)

%p         if n = 1 then

%p                 4;

%p         else

%p                 procname(n-1)*(procname(n-1)-1) ;

%p         end if;

%p end proc:

%p seq(A204321(n),n=1..10) ; # _R. J. Mathar_, Jan 19 2012

%t Join[{a = 4}, Table[a = a^2 - a, {n, 9}]] (* _Vladimir Joseph Stephan Orlovsky_, Feb 24 2012 *)

%t RecurrenceTable[{a[1]==4, a[n] == a[n-1]*(a[n-1]-1)}, a, {n, 1, 10}] (* _Vaclav Kotesovec_, Dec 18 2014 *)

%t NestList[#^2-#&,4,10] (* _Harvey P. Dale_, Jun 20 2023 *)

%K nonn

%O 1,1

%A _Daniel Chiverton_, Jan 14 2012