A108768 Primes that appear in the sequence p:=x^2+x+1, sieved with a quadratic sieve construction.

3, 7, 13, 7, 31, 43, 19, 73, 13, 37, 19, 157, 61, 211, 241, 307, 127, 421, 463, 79, 601, 31, 37, 757, 271, 67, 331, 151, 1123, 397, 97, 43, 67, 1483, 223, 547, 1723, 139, 631, 283, 109, 103, 61, 181, 2551, 379, 919, 409, 2971, 79, 103, 3307, 163, 3541, 523, 97, 3907

Offset: 1

Author

Bernhard Helmes (pi(AT)devalco.de), Jun 24 2005

Keywords

• nonn
• uned
• obsc

Comments

This sequence appears in a website available on web.archive (see Quadratic Sieve Construction link). There is a single appearance of the first term 3, while all other primes appear twice. See A256148 for a version of the sequence consistent with the current version of the website where each prime appears only once. - Ray Chandler, Jul 05 2015

Links

• Bernhard Helmes, Prime sieving on the polynomial f(n)=n^2+n+1.
• Bernhard Helmes, Quadratic Sieve Construction (web.archive).

Crossrefs

Cf. A002061, A002383, A007645, A162471, A256148.

Programs

MuPAD

// from Quadratic Sieve Construction link.
liste_max:=10000;
for x from 1 to liste_max do
    liste_x[x]:=x^2+x+1;
    liste_prim[x]:=1;
end_for;
x:=1;
while (x1) then
     print ("Prim ", p, "x = ", x, isprime (p)) ;
     // Aussiebung
     while (stelleRay Chandler, Jul 05 2015