A207838 - OEIS

%I #31 Dec 08 2023 06:26:16

%S 6,12,114,120,324,336,390,420,498,504,540,672,756,768,840,852,876,

%T 1014,1062,1092,1122,1170,1188,1248,1266,1314,1344,1398,1440,1470,

%U 1524,1758,1770,1818,1860,1968,2028,2046,2088,2184,2190,2232,2262,2268,2304,2382,2430

%N Numbers k such that 5*k^4 + 1 is prime.

%C All terms are multiples of 6.

%H Vincenzo Librandi, <a href="/A207838/b207838.txt">Table of n, a(n) for n = 1..3000</a>

%F a(n) = ((A207837(n) - 1)/5)^1/4. - _Paul F. Marrero Romero_, Dec 07 2023

%t Select[Range[2440], PrimeQ[5 #^4 + 1] &] (* by definition *)

%o (PARI) for(n=1, 406, r=6480*n^4+1; if(isprime(r), print1(6*n", ")));

%o (Magma) [6*n: n in [1..406] | IsPrime(6480*n^4+1)];

%Y Cf. A207837 (primes of the form 5*k^4+1).

%Y Cf. A005097, A111051, A115104.

%K nonn,easy

%O 1,1

%A _Bruno Berselli_, Feb 21 2012