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 A057327 #16 Aug 13 2024 15:47:51 %S A057327 1531,2131,2311,3061,6211,6841,7411,10321,13681,15391,16651,18121, %T A057327 22531,23011,24391,29671,30781,31771,33301,35311,41491,44371,46411, %U A057327 54601,56311,57991,60331,61381,66601,67651,78031,83431,85381,88741 %N A057327 First member of a prime quadruple in a 2p-1 progression. %C A057327 Numbers n such that n remains prime through 3 iterations of function f(x) = 2x - 1. %H A057327 Harvey P. Dale, <a href="/A057327/b057327.txt">Table of n, a(n) for n = 1..1000</a> %H A057327 <a href="/index/Pri#primes_AP">Index entries for sequences related to primes in arithmetic progressions</a> %e A057327 Quadruplets are (1531,3061,6121,12241), (2131,4261,8521,17041), ... %t A057327 Select[Prime[Range[9000]],And@@PrimeQ[NestList[2#-1&,#,3]]&] (* _Harvey P. Dale_, May 27 2012 *) %Y A057327 Cf. (A005382 and A005383), A057326, A057328, A057329, A057330, A005603. %K A057327 nonn %O A057327 1,1 %A A057327 _Patrick De Geest_, Aug 15 2000 %E A057327 Offset changed by _Andrew Howroyd_, Aug 13 2024