|
|
A243818
|
|
Primes p for which p^i - 4 is prime for i = 1, 3 and 5.
|
|
3
|
|
|
11, 971, 1877, 2861, 8741, 12641, 13163, 16763, 28283, 29021, 30707, 36713, 41957, 42227, 58967, 98717, 105971, 115127, 128663, 138641, 160817, 164093, 167441, 190763, 205607, 210173, 211067, 228341, 234197, 237977, 246473, 249107, 276557, 295433, 312233
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
1,1
|
|
COMMENTS
|
This is a subsequence of the following:
A046132: Larger member p+4 of cousin primes (p, p+4).
A243817: Primes p for which p - 4 and p^3 - 4 are primes.
|
|
LINKS
|
|
|
EXAMPLE
|
p = 11 is in this sequence because p - 4 = 7 (prime), p^3 - 4 = 1327 (prime) and p^5 - 4 = 161047 (prime).
p = 971 is in this sequence because p - 4 = 967 (prime), p^3 - 4 = 915498607 (prime) and p^5 - 4 = 863169625893847 (prime).
|
|
MATHEMATICA
|
Select[Range[300000], PrimeQ[#] && AllTrue[#^{1, 3, 5} - 4, PrimeQ] &] (* Amiram Eldar, Apr 04 2020 *)
Select[Prime[Range[27000]], AllTrue[#^{1, 3, 5}-4, PrimeQ]&] (* Harvey P. Dale, Jan 04 2021 *)
|
|
PROG
|
(Python)
import sympy.ntheory as snt
n=5
while n>1:
....n1=n-4
....n2=((n**3)-4)
....n3=((n**5)-4)
....##Check if n1 , n2 and n3 are also primes.
....if snt.isprime(n1)== True and snt.isprime(n2)== True and snt.isprime(n3)== True:
........print(n, n1, n2, n3)
....n=snt.nextprime(n)
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn,easy
|
|
AUTHOR
|
|
|
STATUS
|
approved
|
|
|
|