OFFSET
1,1
COMMENTS
Schinzel proved in 1958 that the set of primes of kind n^(2^k) + 1, n^(2^k) + 3, n^(2^k) + 7 and n^(2^k) + 9 is infinite for each number k > 0.
REFERENCES
Sierpinski, W. Elementary theory of numbers. Warszawa 1964 Monografie Matematyczne Vol. 42.
LINKS
Robert Israel, Table of n, a(n) for n = 1..500
MAPLE
R:= NULL: count:= 0:
for k from 0 while count < 30 do
for i in [20, 30, 40, 50] do
n:= 70*k + i;
if isprime(n^4+1) and isprime(n^4+3) and isprime(n^4+7) and isprime(n^4+9) then
count:= count+1; R:= R, n;
fi
od od:
R; # Robert Israel, Feb 11 2021
MATHEMATICA
Select[Range[109*10^5], AllTrue[#^4+{1, 3, 7, 9}, PrimeQ]&] (* Harvey P. Dale, May 15 2022 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Artur Jasinski, Dec 09 2006
EXTENSIONS
Corrected and extended by Donovan Johnson, Apr 22 2008
STATUS
approved