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 A055197 #19 Mar 01 2020 05:42:24
%S A055197 10,14,16,19,20,21,25,26,27,28,30,31,32,33,34,35,38,39,41,42,43,44,45,
%T A055197 46,47,48,49,50,51,52,54,56,57,58,64,65,66,67,70,71,72,73,75,76,77,78,
%U A055197 79,80,81,82,84,85,87,88,89,90,91,92,94,95,96,98,99,100
%N A055197 Numbers k such that A005728(k) is not prime.
%C A055197 From a question posed by Leo Moser.
%D A055197 Martin Gardner, "The Last Recreations," Chapter entitled "Strong Laws of Small Primes," Copernicus, Springer-Verlag, NY, 1997, page 199.
%H A055197 Amiram Eldar, <a href="/A055197/b055197.txt">Table of n, a(n) for n = 1..10000</a>
%H A055197 Leo Moser, <a href="https://books.google.com/books?id=u6N0yfe69RcC&pg=PA312">Problem P42</a>, Canadian Mathematical Bulletin, Vol. 5, No. 3 (1962), pp. 312-313.
%t A055197 s=1; Do[ s=s+EulerPhi[ n ]; If[ !PrimeQ[ s ], Print[ n ] ], {n, 1, 100} ]
%Y A055197 Cf. A005728.
%Y A055197 Complement of A055201.
%K A055197 easy,nonn
%O A055197 1,1
%A A055197 _Robert G. Wilson v_, Jul 04 2000
%E A055197 Offset corrected by _Amiram Eldar_, Mar 01 2020