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 A014573 #23 Feb 16 2025 08:32:33 %S A014573 3,0,1,2,4,8,12,32,36,40,24,48,160,396,2268,704,312,72,336,216,936, %T A014573 144,624,1056,1760,360,2560,384,288,1320,3696,240,768,9000,432,7128, %U A014573 4200,480,576,1296,1200,15936,3312,3072,3240,864,3120,7344,3888,720,1680 %N A014573 Smallest k such that phi(x) = k has exactly n solutions, n>=0 with Carmichael conjecture. %C A014573 Carmichael conjectured that no term exists for n=1. %D A014573 M. Abramowitz and I. A. Stegun, eds., Handbook of Mathematical Functions, National Bureau of Standards Applied Math. Series 55, 1964 (and various reprintings), p. 840. %H A014573 M. Abramowitz and I. A. Stegun, eds., <a href="http://www.convertit.com/Go/ConvertIt/Reference/AMS55.ASP">Handbook of Mathematical Functions</a>, National Bureau of Standards, Applied Math. Series 55, Tenth Printing, 1972 [alternative scanned copy]. %H A014573 Max Alekseyev, <a href="https://oeis.org/wiki/User:Max_Alekseyev/gpscripts">PARI/GP Scripts for Miscellaneous Math Problems</a> (invphi.gp). %H A014573 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/CarmichaelsTotientFunctionConjecture.html">Carmichael's Totient Function conjecture</a> %o A014573 (PARI) a(n) = if (n==1, 0, my(k=1); while (#invphi(k) != n, k++); k); \\ using invphi in PARI scripts link; _Michel Marcus_, Oct 09 2023 %Y A014573 Cf. A000010. Essentially same as A007374, which is the main entry for this sequence. %K A014573 nonn,easy %O A014573 0,1 %A A014573 _Eric W. Weisstein_ %E A014573 Link fixed by _Charles R Greathouse IV_, Oct 06 2009