A370156 Primes p such that (p-2)/3 is prime and 3*p+2 is composite.
11, 41, 53, 71, 113, 131, 179, 251, 311, 449, 491, 521, 593, 599, 683, 701, 719, 773, 809, 881, 941, 1049, 1061, 1103, 1151, 1229, 1301, 1319, 1373, 1439, 1499, 1511, 1571, 1709, 1733, 1931, 2273, 2309, 2393, 2579, 2591, 2663, 2843, 2861, 2903, 3041, 3119
Offset: 1
Keywords
Examples
(11-2)/3 is a prime and 3*11+2 isn't.
Links
- Robert Israel, Table of n, a(n) for n = 1..10000
Programs
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Maple
filter:= proc(p) isprime(p) and isprime((p-2)/3) and not isprime(3*p+2) end proc: select(filter, [seq(i,i=5..10000,6)]); # Robert Israel, Feb 28 2025
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Mathematica
Select[Prime[Range[500]], ! PrimeQ[3 # + 2] && PrimeQ[(# - 2)/3] &]
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PARI
isok(p) = if (isprime(p), !isprime(3*p+2) && (((p%3) == 2) && isprime((p-2)/3))); \\ Michel Marcus, Feb 17 2024
Comments