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 A266269 #27 Jan 26 2025 20:53:04
%S A266269 2,3,7,211,30031,223092871,13082761331670031,
%T A266269 3217644767340672907899084554131,
%U A266269 1492182350939279320058875736615841068547583863326864530411,16516447045902521732188973253623425320896207954043566485360902980990824644545340710198976591011245999111
%N A266269 a(n) is the smallest number k such that phi(k) >= n*phi(k-1).
%C A266269 For the known terms, we have a(n) = 1 + A002110(A256968(n)) = 1 + A091439(n), which likely holds for most (if not all) terms overall. - _Max Alekseyev_, Jan 26 2025
%H A266269 Max Alekseyev, <a href="/A266269/b266269.txt">Table of n, a(n) for n = 1..12</a>
%e A266269 a(3) = 7 because 7 is the smallest number k such that phi(k) >= n*phi(k-1); phi(7) = 6 >= 3*phi(6) = 3*2.
%o A266269 (Magma) a:=func<n | exists(r){k:k in[2..10^7] | Floor(EulerPhi(k) / EulerPhi(k-1)) eq n}select r else 0>; [a(n):n in[1..5]];
%o A266269 (PARI) a(n) = {my(k=2, e=1); while(n*e > e=eulerphi(k), k++); k; } \\ _Jinyuan Wang_, Nov 01 2020
%Y A266269 Cf. A000010, A002110, A091439, A091456, A256968, A266276.
%K A266269 nonn
%O A266269 1,1
%A A266269 _Jaroslav Krizek_, Jan 26 2016
%E A266269 a(6)-a(8) from _Jinyuan Wang_, Nov 01 2020
%E A266269 a(9)-a(10) from _Max Alekseyev_, Jan 25 2025