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 A290805 #34 Dec 08 2024 17:16:24 %S A290805 561,1729,63973,1729,367939585,63973,294409,232289960085001, %T A290805 11570858964626401,79939760257,509033161,611559276803883001, %U A290805 13079177569,27685385948423487745,26979791457662785,287290964059686145,13046319747121261903830001,7847507962539316696504321,993942550111105,6280552422566791778305,24283361157780097,759608966313690599499265,6657107145346817668085761,283219223388059484626764342346640001 %N A290805 Least Carmichael number whose Euler totient function value is an n-th power. %C A290805 Banks proved that for each positive integer N there are an infinite number of Carmichael numbers whose Euler totient function value is an N-th power. Therefore this sequence is infinite. %C A290805 For any n > 26, a(n) > 10^22. - _Amiram Eldar_, Apr 20 2024 %H A290805 Max Alekseyev, <a href="/A290805/b290805.txt">Table of n, a(n) for n = 1..60</a> %H A290805 William D. Banks, <a href="http://dx.doi.org/10.4153/CMB-2009-001-7">Carmichael Numbers with a Square Totient</a>, Canadian Mathematical Bulletin, Vol. 52, No. 1 (2009), pp. 3-8. %H A290805 Claude Goutier, <a href="http://www-labs.iro.umontreal.ca/~goutier/OEIS/A055553/">Compressed text file carm10e22.gz containing all the Carmichael numbers up to 10^22</a>. %H A290805 R. G. E. Pinch, <a href="http://s369624816.websitehome.co.uk/rgep/carpsp.html">Tables relating to Carmichael numbers</a>. %e A290805 phi(1729) = 36^2 = 6^4 while phi(561) and phi(1105) are not perfect powers, therefore a(2) = a(4) = 1729. %Y A290805 Cf. A000010, A002997, A272798, A292573. %K A290805 nonn %O A290805 1,1 %A A290805 _Amiram Eldar_, Aug 11 2017 %E A290805 Terms up to a(13) were calculated using Pinch's tables of Carmichael numbers. %E A290805 a(1) prepended by _David A. Corneth_, Aug 11 2017 %E A290805 a(14)-a(16), a(19)-a(21), a(25)-a(26) calculated using data from _Claude Goutier_ and added by _Amiram Eldar_, Apr 20 2024 %E A290805 a(17)-a(18), a(22)-a(24) from _Max Alekseyev_, Apr 25 2024 %E A290805 Edited by _Max Alekseyev_, Dec 04 2024