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A219586 Greatest prime factor of the product Prod{x<=n} x^2+1. 0
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 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..51.

C. Hooley, On the greatest prime factor of a quadratic polynomial, Acta Mathematica July 1967, Volume 117, Issue 1, pp 281-299.

PROG

(PARI) a(m) = {for (n=1, m, f = factor(prod(x=1, n, x^2+1)); print1(f[length(f~), 1], ", "); ); }

CROSSREFS

Cf. A002496, A002522, A005574, A014442.

Sequence in context: A281793 A259036 A081235 * A082534 A165659 A154816

Adjacent sequences:  A219583 A219584 A219585 * A219587 A219588 A219589

KEYWORD

nonn

AUTHOR

Michel Marcus, Nov 23 2012

STATUS

approved

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Last modified March 24 06:56 EDT 2019. Contains 321444 sequences. (Running on oeis4.)