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A243861
Primes p for which p^i - 4 is prime for i = 1, 3, 5 and 7.
2
971, 12641, 205607, 228341, 276557, 412343, 1012217, 1101323, 1902881, 2171021, 2477411, 2692121, 4116377, 4311677, 6060953, 6182993, 6388913, 6444863, 8341121, 8551451, 9507527, 10523141, 10997411, 11444093, 14101361, 14656307, 14813147, 15435587, 17337521
OFFSET
1,1
COMMENTS
Subsequence of A243818: Primes p for which p^i - 4 is prime for i = 1, 3 and 5.
LINKS
EXAMPLE
Prime p=971 is in this sequence because p-4 = 967 (prime), p^3-4 = 915498607 (prime), p^5-4 = 863169625893847 (prime), and p^7-4 = 813831713247384370687 (prime).
PROG
(Python)
import sympy.ntheory as snt
n=2
while n>1:
....n1=n-4
....n2=((n**3)-4)
....n3=((n**5)-4)
....n4=((n**7)-4)
....##Check if n1 , n2, n3 and n4 are also primes.
....if snt.isprime(n1)== True and snt.isprime(n2)== True and snt.isprime(n3)== True and snt.isprime(n4)== True:
........print(n, n1, n2, n3, n4)
....n=snt.nextprime(n)
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Abhiram R Devesh, Jun 12 2014
STATUS
approved