OFFSET
1,1
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).
PROG
(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 (x<liste_max) do
stelle:=x;
p:=liste_x[x];
if (p>1) then
print ("Prim ", p, "x = ", x, isprime (p)) ;
// Aussiebung
while (stelle<liste_max) do
erg:=liste_x[stelle];
while (erg mod p = 0) do
erg:=erg /p;
end_while;
liste_x[stelle]:=erg;
liste_prim[stelle]:=0;
// print ("x= ", stelle, erg, p);
stelle:=stelle+p;
end_while;
end_if;
x:=x+1;
end_while;
// Ray Chandler, Jul 05 2015
CROSSREFS
KEYWORD
nonn,uned,obsc
AUTHOR
Bernhard Helmes (pi(AT)devalco.de), Jun 24 2005
STATUS
approved