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 A333912 #10 Apr 12 2020 09:50:15 %S A333912 29,58,61,77,93,99,113,122,124,141,145,154,157,169,186,188,198,226, %T A333912 232,237,241,253,282,287,290,301,305,314,316,317,325,338,348,349,363, %U A333912 369,381,385,387,413,429,441,449,465,474,482,484,488,493,495,496,506,508,509 %N A333912 Numbers k such that phi(k) is not the sum of 3 squares, where phi is the Euler totient function (A000010). %C A333912 Pollack (2011) proved that the complementary sequence has asymptotic density 7/8. Therefore the asymptotic density of this sequence is 1/8. %H A333912 Amiram Eldar, <a href="/A333912/b333912.txt">Table of n, a(n) for n = 1..10000</a> %H A333912 Paul Pollack, <a href="https://www.emis.de/journals/INTEGERS/papers/l13/l13.Abstract.html">Values of the Euler and Carmichael functions which are sums of three squares</a>, Integers, Vol. 11 (2011), pp. 145-161. %e A333912 1 is not a term since phi(1) = 1 = 0^2 + 0^2 + 1^2 is the sum of 3 squares. %e A333912 29 is a term since phi(29) = 28 is not the sum of 3 squares. %t A333912 Select[Range[500], SquaresR[3, EulerPhi[#]] == 0 &] %Y A333912 Cf. A000010, A004215, A039770, A272405, A333909, A333913. %K A333912 nonn %O A333912 1,1 %A A333912 _Amiram Eldar_, Apr 09 2020