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 A117307 #10 Feb 08 2021 02:56:24
%S A117307 1,2,3,4,6,7,9,13,14,15,16,18,20,21,24,25,26,28,30,33,35,36,39,42,44,
%T A117307 45,50,52,56,66,67,70,72,78,79,81,84,90,121,123,134,139,151,158,162,
%U A117307 163,164,165,176,193,200,203,215,220,221,242,243,245,246,249
%N A117307 Numbers for which (phi(n))^2+phi(n)+1 is a prime number.
%H A117307 Amiram Eldar, <a href="/A117307/b117307.txt">Table of n, a(n) for n = 1..10000</a>
%e A117307 14 is in the sequence because (phi(14))^2+phi(14)+1 = 6^2+6+1 = 43, which is a prime number.
%t A117307 f[x_] := x^2 + x + 1; Select[Range[250], PrimeQ[f[EulerPhi[#]]] &] (* _Amiram Eldar_, Feb 08 2021 *)
%o A117307 (PARI) lista(nn) = {for (n = 1, nn, if (isprime((eulerphi(n))^2 + eulerphi(n) + 1), print1(n, ", ")););} \\ _Michel Marcus_, Jun 01 2013
%Y A117307 Cf. A000010, A002384.
%K A117307 nonn
%O A117307 1,2
%A A117307 Luc Stevens (lms022(AT)yahoo.com), Apr 24 2006
%E A117307 Corrected by _Michel Marcus_, Jun 01 2013