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A276124
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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, 4, 22, 589, 399253, 41144206447, 77387327118194895379, 10169897514576967837097322386922878932, 259050897146323086186965020577200627526185475088368701480903471601830
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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-1)*a(n-2)-a(n-1)*a(n-3)-a(n-2)*a(n-3)-a(n-4).
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MATHEMATICA
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RecurrenceTable[{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], a[0] == a[1] == a[2] == a[3] == 1}, a, {n, 0, 11}] (* Michael De Vlieger, Aug 21 2016 *)
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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)
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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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