cp's OEIS Frontend

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.

A250027 Primes p such that f(p) and f(f(p)) are primes, where f(x) = x^2+3*x+1.

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%I A250027 #17 Sep 08 2022 08:46:10
%S A250027 3,19,29,59,113,373,379,419,449,593,643,929,983,1063,1423,2053,2069,
%T A250027 3169,3593,3943,4159,4493,5153,6163,6659,6689,6869,6949,7583,8963,
%U A250027 9629,10099,10103,12413,13963,14303,14639,15359,15649,16703,17099,18523,18869
%N A250027 Primes p such that f(p) and f(f(p)) are primes, where f(x) = x^2+3*x+1.
%H A250027 Zak Seidov, <a href="/A250027/b250027.txt">Table of n, a(n) for n = 1..1000</a>
%t A250027 Select[Range[25000], PrimeQ[#] && PrimeQ[#^2 + 3 # + 1] && PrimeQ[#^4 + 6 #^3 + 14 #^2 + 15 # + 5] &] (* _Vincenzo Librandi_, Nov 19 2014 *)
%o A250027 (Magma) f:=func<i | i^2+3*i+1>; [p: p in PrimesUpTo(22000) | IsPrime(f(p)) and IsPrime(f(f(p)))]; // _Vincenzo Librandi_, Nov 19 2014
%Y A250027 Subsequence of A094210 and of A153590.
%K A250027 nonn
%O A250027 1,1
%A A250027 _Zak Seidov_, Nov 11 2014