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A219586
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Greatest prime factor of Product_{x=1..n} (x^2 + 1).
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0
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2, 5, 5, 17, 17, 37, 37, 37, 41, 101, 101, 101, 101, 197, 197, 257, 257, 257, 257, 401, 401, 401, 401, 577, 577, 677, 677, 677, 677, 677, 677, 677, 677, 677, 677, 1297, 1297, 1297, 1297, 1601, 1601, 1601, 1601, 1601, 1601, 1601, 1601, 1601, 1601, 1601, 1601
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internal format)
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OFFSET
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1,1
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LINKS
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MAPLE
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a:= proc(n) option remember; `if`(n=0, 0,
max(a(n-1), numtheory[factorset](n^2+1)[]))
end:
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MATHEMATICA
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a[n_] := a[n] = If[n == 1, 2, Max[a[n-1], FactorInteger[n^2+1][[-1, 1]]]];
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PROG
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(PARI) a(m) = {for (n=1, m, f = factor(prod(x=1, n, x^2+1)); print1(f[length(f~), 1], ", "); ); }
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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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