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 A319313 #7 Dec 23 2024 14:53:45
%S A319313 6,2,20,3,1008,4,72,5,4400,144,835660800,7,10800,8,272,9,9849600,400,
%T A319313 208039104,11,145520912351232000000,64281600,
%U A319313 3608344625286776094720000,13,1296,84672,90944,129600
%N A319313 a(n) is the least integer m such that A047994(m) = ((n-2)/n)*m where A047994 is the unitary totient function, or 0 if there is no such m.
%H A319313 Yasutoshi Kohmoto, <a href="https://web.archive.org/web/*/http://list.seqfan.eu/oldermail/seqfan/2018-August/018717.html">UnitaryPhi</a>, SeqFan list, Aug-Sep 2018.
%F A319313 a(2n) = A318842(n).
%o A319313 (PARI) \\ uses the "solve_uphi pari code", see A318842 links
%o A319313 a(n) = {my(lim = 1, v); while (1, v = solve_uphi(n-2, n, lim); if (#v, return (v[1])); lim *= 10; ); }
%Y A319313 Cf. A047994 (unitary totient).
%Y A319313 Cf. A030163, A305678, A318842.
%K A319313 nonn,more
%O A319313 3,1
%A A319313 _Michel Marcus_, Sep 17 2018