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A350676
Primes p such that p^2 + 2*p + 4 is prime.
1
3, 7, 13, 37, 61, 73, 139, 157, 229, 241, 349, 367, 397, 433, 439, 457, 523, 541, 601, 619, 709, 727, 751, 769, 787, 859, 919, 1069, 1129, 1153, 1237, 1381, 1459, 1609, 1627, 1699, 1783, 1801, 2029, 2221, 2239, 2347, 2467, 2557, 2659, 2719, 2767, 3001, 3019, 3253, 3331, 3391, 3547, 3673, 3691
OFFSET
1,1
LINKS
EXAMPLE
a(3) = 13 is a term because 13 and 13^2 + 2*13 + 4 = 199 are prime.
MAPLE
select(p -> isprime(p^2+2*p+4), [seq(ithprime(i), i=1..1000)]);
PROG
(Python)
from sympy import isprime
for p in range (2, 3700):
if isprime(p) and isprime(p**2 + 2*p + 4):
print (p, end=", ") # Karl-Heinz Hofmann, Jan 11 2022
CROSSREFS
Sequence in context: A106057 A049492 A166283 * A186721 A177945 A147448
KEYWORD
nonn
AUTHOR
J. M. Bergot and Robert Israel, Jan 10 2022
STATUS
approved