This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A101794 #9 May 13 2024 02:14:56 %S A101794 45,90,675,885,3030,4290,6870,13410,14460,15855,17850,18675,20625, %T A101794 21885,25350,26820,26925,28230,30525,30705,31710,31785,33375,34860, %U A101794 41685,41940,57435,63420,63570,71805,74025,78585,83865,85230,93075 %N A101794 Numbers k such that 4*k-1, 8*k-1, 16*k-1 and 32*k-1 are all primes. %H A101794 Amiram Eldar, <a href="/A101794/b101794.txt">Table of n, a(n) for n = 1..10000</a> %e A101794 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 A101794 Select[Range[10^5], And @@ PrimeQ[2^Range[2, 5]*# - 1] &] (* _Amiram Eldar_, May 13 2024 *) %o A101794 (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 A101794 Cf. A002515, A101795, A101796, A101797, A101798. %Y A101794 Subsequence of A005099, A005122 and A101790. %Y A101794 Subsequence: A101994. %K A101794 easy,nonn %O A101794 1,1 %A A101794 Douglas Stones (dssto1(AT)student.monash.edu.au), Dec 16 2004