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a(0) = 4; for n>0, a(n) = a(n-1)^2 - 10.
0

%I #8 Apr 07 2021 02:49:57

%S 4,6,26,666,443546,196733054106,38703894577874323459226,

%T 1497991455495209454913926565546156918884519066,

%U 2243978400736656089037771915607429213031952311714405870405411591378207718779971154117512346

%N a(0) = 4; for n>0, a(n) = a(n-1)^2 - 10.

%H A. V. Aho and N. J. A. Sloane, <a href="https://www.fq.math.ca/Scanned/11-4/aho-a.pdf">Some doubly exponential sequences</a>, Fibonacci Quarterly, Vol. 11, No. 4 (1973), pp. 429-437, <a href="http://neilsloane.com/doc/doubly.html">alternative link</a>.

%F a(n) ~ c^(2^n), where c = 2.25389493024591818564987473260518595497528199646373551430047151255211... . - _Vaclav Kotesovec_, May 21 2015

%t RecurrenceTable[{a[n]==a[n-1]^2-10, a[0]==4},a,{n,0,10}] (* _Vaclav Kotesovec_, May 21 2015 *)

%K nonn

%O 0,1

%A _N. J. A. Sloane_, Nov 12 2004