OFFSET
1,1
COMMENTS
The generalized Bunyakovsky conjecture implies that there are infinitely many terms, in fact infinitely many for which q = p+2 and r = p+6. - Robert Israel, Oct 21 2021
LINKS
Robert Israel, Table of n, a(n) for n = 1..10000
EXAMPLE
a(1) = 11 is a term because with p=11, q=13, r=17 we have p^2+q+r = 151, p+q^2+r = 197, p+q+r^2 = 313, all of which are primes.
MAPLE
R:= NULL: count:= 0:
p:= 2: q:= 3: r:= 5:
while count < 50 do
p:= q; q:= r; r:= nextprime(r);
if andmap(isprime, [p^2+q+r, p+q^2+r, p+q+r^2]) then
count:= count+1; R:= R, p;
fi
od:
R;
MATHEMATICA
Select[Partition[Select[Range[350000], PrimeQ], 3, 1], And @@ PrimeQ[{#[[1]]^2 + #[[2]] + #[[3]], #[[1]] + #[[2]]^2 + #[[3]], #[[1]] + #[[2]] + #[[3]]^2}] &][[;; , 1]] (* Amiram Eldar, Oct 14 2021 *)
PROG
(Python)
from itertools import islice
from sympy import nextprime, isprime
def A348353(): # generator of terms.
p, q, r = 2, 3, 5
while True:
if isprime(p*p+q+r) and isprime(p+q*q+r) and isprime(p+q+r*r):
yield p
p, q, r = q, r, nextprime(r)
CROSSREFS
KEYWORD
nonn
AUTHOR
J. M. Bergot and Robert Israel, Oct 14 2021
STATUS
approved