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 A051478 #16 Nov 05 2024 19:00:17 %S A051478 4,2,0,4,2,0,2,0,0,4,2,0,2,2,0,2,2,0,2,2,0,0,0,0,2,2,2,0,0,0,2,2,0,2, %T A051478 0,0,2,0,0,4,2,0,0,2,0,0,2,0,2,0,0,2,0,0,2,2,0,0,2,0,0,2,0,0,2,0,2,0, %U A051478 0,2,0,0,2,0,0,2,2,0,0,0,0,2,0,0,2,2,0,0,2,0,2,0,0,2,2,0,0,0,0,0,0,0,0 %N A051478 a(n) is the number of values k satisfying phi(k) = 4*n+2, n>0. %C A051478 Sequence consists of only 0's, 2's and 4's. %H A051478 Amiram Eldar, <a href="/A051478/b051478.txt">Table of n, a(n) for n = 1..10000</a> %H A051478 Max Alekseyev, <a href="https://oeis.org/wiki/User:Max_Alekseyev/gpscripts">PARI/GP Scripts for Miscellaneous Math Problems</a> (invphi.gp). %e A051478 phi(k) = 4*1+2 has 4 solutions (k = 7, 9, 14, 18), so a(1) = 4. %o A051478 (PARI) a(n) = invphiNum(4*n+2); \\ _Amiram Eldar_, Nov 05 2024, using _Max Alekseyev_'s invphi.gp %Y A051478 Cf. A000010, A032446, A051479. %K A051478 nonn %O A051478 1,1 %A A051478 _Jud McCranie_