A089123 Smallest prime factor of numbers of the form A^2 + 3.

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

Offset

1,1

References

H. Rademacher, Lectures on Elementary Number Theory, pp. 33-38.

Links

Harvey P. Dale, Table of n, a(n) for n = 1..1000

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

Adjacent sequences: A089120 A089121 A089122 * A089124 A089125 A089126

Keyword

easy,nonn

Author

Cino Hilliard, Dec 05 2003

Status

approved