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A089123 Smallest prime factor of numbers of the form A^2 + 3. 1
2, 7, 2, 19, 2, 3, 2, 67, 2, 103, 2, 3, 2, 199, 2, 7, 2, 3, 2, 13, 2, 487, 2, 3, 2, 7, 2, 787, 2, 3, 2, 13, 2, 19, 2, 3, 2, 1447, 2, 7, 2, 3, 2, 7, 2, 13, 2, 3, 2, 2503, 2, 2707, 2, 3, 2, 43, 2, 7, 2, 3, 2, 3847, 2, 4099, 2, 3, 2, 7, 2, 4903, 2, 3, 2, 5479, 2, 5779, 2, 3, 2, 19, 2, 7, 2, 3, 2, 7 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
REFERENCES
H. Rademacher, Lectures on Elementary Number Theory, pp. 33-38.
LINKS
MATHEMATICA
FactorInteger[#][[1, 1]]&/@(Range[90]^2+3) (* Harvey P. Dale, Apr 22 2018 *)
PROG
(PARI) smallasqp3(m) = { for(a=1, m, y=a^2 + 3; f = factor(y); v = component(f, 1); v1 = v[length(v)]; print1(v[1]", ") ) }
CROSSREFS
Cf. A002496.
Sequence in context: A222654 A318059 A212835 * A281751 A282366 A281897
KEYWORD
easy,nonn
AUTHOR
Cino Hilliard, Dec 05 2003
STATUS
approved

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Last modified June 13 15:42 EDT 2024. Contains 373389 sequences. (Running on oeis4.)