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A276271
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a(0) = a(1) = a(2) = a(3) = 1; for n > 3, a(n) = (a(n-1)^2+a(n-2)^2+a(n-3)^2+a(n-1)+a(n-2)+a(n-3))/a(n-4).
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2
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1, 1, 1, 1, 6, 46, 2206, 4870846, 3954191749561, 339905052007042640998641, 52373274877565894156748130733610185904753361, 563138297002425210235477817802336090254190075906443582099838858026136728896536841
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listen;
history;
text;
internal format)
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OFFSET
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0,5
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LINKS
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FORMULA
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a(n) = 8*a(n-1)*a(n-2)*a(n-3)-a(n-4)-1.
a(n) ~ 2^(-3/2) * c^(d^n), where c = 1.2578918597... and d = A058265 = 1.83928675521416... = (1 + (19 + 3*sqrt(33))^(1/3) + (19 - 3*sqrt(33))^(1/3))/3. - Vaclav Kotesovec, Mar 20 2017
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MATHEMATICA
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nxt[{a_, b_, c_, d_}]:={b, c, d, (b^2+c^2+d^2+b+c+d)/a}; NestList[nxt, {1, 1, 1, 1}, 12][[All, 1]] (* Harvey P. Dale, Mar 10 2017 *)
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PROG
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(Ruby)
def A(m, n)
a = Array.new(m, 1)
ary = [1]
while ary.size < n + 1
i = a[1..-1].inject(0){|s, i| s + i * i} + a[1..-1].inject(:+)
break if i % a[0] > 0
a = *a[1..-1], i / a[0]
ary << a[0]
end
ary
end
A(4, n)
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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STATUS
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approved
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