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A121897
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a(n) = 4*a(n-1)*a(n-2)*a(n-3)*a(n-4) - a(n-5).
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3
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1, 1, 1, 1, 1, 3, 11, 131, 17291, 298995971, 29799530324409601, 80728364323218860837749108564353, 49748616842002716055120167595193322161740083228987208037683201
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OFFSET
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1,6
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LINKS
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MAPLE
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a:= proc(n) option remember;
if n<6 then 1
else 4*a(n-1)*a(n-2)*a(n-3)*a(n-4) - a(n-5)
fi;
end:
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MATHEMATICA
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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}]
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 *)
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PROG
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(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
(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
(Sage)
def a(n):
if (n<6): return 1
else: return 4*a(n-1)*a(n-2)*a(n-3)*a(n-4) - a(n-5)
(GAP)
a:= function(n)
if n<6 then return 1;
else return 4*a(n-1)*a(n-2)*a(n-3)*a(n-4) - a(n-5);
fi;
end;
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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