%I #9 May 13 2024 02:14:56
%S 45,90,675,885,3030,4290,6870,13410,14460,15855,17850,18675,20625,
%T 21885,25350,26820,26925,28230,30525,30705,31710,31785,33375,34860,
%U 41685,41940,57435,63420,63570,71805,74025,78585,83865,85230,93075
%N Numbers k such that 4*k-1, 8*k-1, 16*k-1 and 32*k-1 are all primes.
%H Amiram Eldar, <a href="/A101794/b101794.txt">Table of n, a(n) for n = 1..10000</a>
%e 4*45-1 = 179, 8*45-1 = 359, 16*45-1 = 719 and 32*45-1 = 1439 are primes, so 45 is a term.
%t Select[Range[10^5], And @@ PrimeQ[2^Range[2, 5]*# - 1] &] (* _Amiram Eldar_, May 13 2024 *)
%o (PARI) is(k) = isprime(4*k-1) && isprime(8*k-1) && isprime(16*k-1) && isprime(32*k-1); \\ _Amiram Eldar_, May 13 2024
%Y Cf. A002515, A101795, A101796, A101797, A101798.
%Y Subsequence of A005099, A005122 and A101790.
%Y Subsequence: A101994.
%K easy,nonn
%O 1,1
%A Douglas Stones (dssto1(AT)student.monash.edu.au), Dec 16 2004