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 A067126 #16 Feb 12 2025 17:52:52
%S A067126 1,2,3,4,5,7,9,11,13,17,19,23,29,31,37,41,43,47,53,59,61,67,71,73,79,
%T A067126 83,89,97,101,103,107,109,113,127,131,137,139,149,151,157,163,167,173,
%U A067126 179,181,191,193,197,199,211,223,227,229,233,239,241,251,257,263,269
%N A067126 Numbers for which phi(n) >= phi(k) for all k = 1 to n-1.
%C A067126 Conjecture: 4 and 9 are the only composite terms.
%C A067126 No more composite terms below 1.5e18. Such a term would require a prime gap greater than sqrt(p); in the absence of such large gaps, a(n) = prime(n-2) for n > 6. - _Charles R Greathouse IV_, Apr 12 2010
%e A067126 4 is a term as phi(4)=2 and phi(1), phi(2), phi(3) are <= 2. 16 is not a term as phi(16) < phi(11).
%t A067126 Join[{1,2,3,4,5,7,9},DeleteDuplicates[Table[{n,EulerPhi[n]},{n,11,280}],GreaterEqual[#1[[2]],#2[[2]]]&][[;;,1]]] (* _Harvey P. Dale_, Feb 12 2025 *)
%K A067126 easy,nonn
%O A067126 1,2
%A A067126 _Amarnath Murthy_, Jan 09 2002
%E A067126 Offset changed by _Andrew Howroyd_, Sep 17 2024