login
A240126
Primes p such that p - 2 and p^3 - 2 are also prime.
4
19, 31, 109, 151, 241, 619, 859, 1489, 1951, 2131, 2791, 2971, 3559, 4129, 4651, 4789, 4801, 5659, 6661, 6781, 7591, 8221, 8629, 8821, 8971, 9241, 9721, 9931, 10891, 11971, 12109, 12541, 13831, 14011, 15271, 15289, 15331, 16831, 17029, 17419, 17839, 17989, 18121, 18541, 20149, 20899, 21019
OFFSET
1,1
COMMENTS
All the terms in the sequence are congruent to 1 mod 3.
LINKS
EXAMPLE
19 is in the sequence because 19 is a prime: 19 - 2 = 17 and 19^3 - 2 = 6857 are also prime.
151 is in the sequence because 151 is a prime: 151 - 2 = 149 and 151^3 - 2 = 3442949 are also prime.
MAPLE
KD := proc() local a, b, d; a:=ithprime(n); b:=a-2; d:=a^3-2; if isprime(b)and isprime(d) then RETURN (a); fi; end: seq(KD(), n=1..10000);
MATHEMATICA
Select[Prime[Range[2000]], PrimeQ[# - 2] && PrimeQ[#^3 - 2] &]
PROG
(PARI) s=[]; forprime(p=2, 22000, if(isprime(p-2) && isprime(p^3-2), s=concat(s, p))); s \\ Colin Barker, Apr 02 2014
CROSSREFS
Intersection of A006512 and A178251.
Sequence in context: A107168 A243450 A237418 * A125602 A139847 A087764
KEYWORD
nonn
AUTHOR
K. D. Bajpai, Apr 01 2014
STATUS
approved