%I #20 May 13 2024 02:14:48
%S 3,45,90,180,255,258,363,378,453,483,615,675,705,873,885,978,1350,
%T 1533,1770,1788,2673,2793,2868,3030,3225,3240,4203,4290,4548,4830,
%U 4998,5103,5253,5295,5568,5775,5955,6060,6138,6870,7383,7713,8133,8370,8580,9000
%N Numbers k such that 4*k-1, 8*k-1 and 16*k-1 are all primes.
%H Amiram Eldar, <a href="/A101790/b101790.txt">Table of n, a(n) for n = 1..10000</a>
%e 4*3 - 1 = 11, 8*3 - 1 = 23 and 16*3 - 1 = 47 are primes, so 3 is a term.
%t Select[Range[10^4], And @@ PrimeQ[2^Range[2, 4]*# - 1] &] (* _Amiram Eldar_, May 12 2024 *)
%o (Magma) [n: n in [0..10000] | IsPrime(4*n-1) and IsPrime(8*n-1) and IsPrime(16*n-1)]; // _Vincenzo Librandi_, Nov 17 2010
%o (PARI) is(k) = isprime(4*k-1) && isprime(8*k-1) && isprime(16*k-1); \\ _Amiram Eldar_, May 12 2024
%Y Cf. A002515, A101791, A101792, A101793.
%Y Subsequence of A005099 and A005122.
%Y Subsequences: A101794, A101994.
%K easy,nonn
%O 1,1
%A Douglas Stones (dssto1(AT)student.monash.edu.au), Dec 16 2004