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%I #13 Sep 08 2022 08:45:27
%S 1,1,1,1,1,3,11,131,17291,298995971,29799530324409601,
%T 80728364323218860837749108564353,
%U 49748616842002716055120167595193322161740083228987208037683201
%N a(n) = 4*a(n-1)*a(n-2)*a(n-3)*a(n-4) - a(n-5).
%H G. C. Greubel, <a href="/A121897/b121897.txt">Table of n, a(n) for n = 1..17</a>
%p a:= proc(n) option remember;
%p if n<6 then 1
%p else 4*a(n-1)*a(n-2)*a(n-3)*a(n-4) - a(n-5)
%p fi;
%p end:
%p seq(a(n), n=1..15); # _G. C. Greubel_, Oct 07 2019
%t a[n_]:= a[n]= If[n<6, 1, 4*a[n-1]*a[n-2]*a[n-3]*a[n-4] - a[n-5]]; Table[a[n], {n, 15}]
%t RecurrenceTable[{a[1]==a[2]==a[3]==a[4]==a[5]==1,a[n]==4a[n-1]a[n-2]a[n-3]a[n-4]-a[n-5]},a,{n,15}] (* _Harvey P. Dale_, Dec 16 2018 *)
%o (PARI) my(m=15, v=concat([1,1,1,1,1], vector(m-5))); for(n=6, m, v[n] = 4*v[n-1]*v[n-2]*v[n-3]*v[n-4] - v[n-5]); v \\ _G. C. Greubel_, Oct 07 2019
%o (Magma) [n lt 6 select 1 else 4*Self(n-1)*Self(n-2)*Self(n-3)*Self(n-4) - Self(n-5): n in [1..15]]; // _G. C. Greubel_, Oct 07 2019
%o (Sage)
%o def a(n):
%o if (n<6): return 1
%o else: return 4*a(n-1)*a(n-2)*a(n-3)*a(n-4) - a(n-5)
%o [a(n) for n in (1..15)] # _G. C. Greubel_, Oct 07 2019
%o (GAP)
%o a:= function(n)
%o if n<6 then return 1;
%o else return 4*a(n-1)*a(n-2)*a(n-3)*a(n-4) - a(n-5);
%o fi;
%o end;
%o List([1..15], n-> a(n) ); # _G. C. Greubel_, Oct 05 2019
%Y Cf. A072879, A121910.
%K nonn
%O 1,6
%A _Roger L. Bagula_, Sep 09 2006
%E Edited by _N. J. A. Sloane_, Sep 15 2006
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