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 A051479 #13 Nov 05 2024 19:08:54 %S A051479 1,4,10,40,121,364,1105,1540,3601,4795,5662,6601,9841,19414,35815, %T A051479 103201,131950,141224,210910,245272,378532,505876,613480,762565, %U A051479 986545,1010527,1147576,1252720,1732847,1750990,1766905,1798951,1863907,2337352,2674042,2773057,3080902 %N A051479 Values of i such that phi(x) = 4i+2 has 4 solutions. %H A051479 Amiram Eldar, <a href="/A051479/b051479.txt">Table of n, a(n) for n = 1..210</a> %H A051479 Max Alekseyev, <a href="https://oeis.org/wiki/User:Max_Alekseyev/gpscripts">PARI/GP Scripts for Miscellaneous Math Problems</a> (invphi.gp). %e A051479 phi(x) = 4*1+2 has 4 solutions (x = 7,9,14,18), so 1 is in the sequence. %o A051479 (PARI) is(k) = invphiNum(4*k+2) == 4; \\ _Amiram Eldar_, Nov 05 2024, using _Max Alekseyev_'s invphi.gp %Y A051479 Cf. A000010, A032446, A051478. %K A051479 nonn %O A051479 1,2 %A A051479 _Jud McCranie_ %E A051479 a(33)-a(37) from _Amiram Eldar_, Nov 05 2024