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 A039777 #28 Jul 28 2024 10:45:12 %S A039777 2,5,21,45,285,765,27645,196605,41067645,72787965,250871805, %T A039777 4295098365,12884901885,23307153405,172130669565,1766029428523005, %U A039777 20978888016396285 %N A039777 Integers m such that phi(m) is equal to the sum of (the product of prime factors) and (the product of exponents) of m-1. %C A039777 No other terms below 10^24. Some large terms: 1039619980803100740810795122685, 32576974833437288924302842789885. - _Max Alekseyev_, Jul 28 2024 %C A039777 All listed terms represent solutions to phi(m) = (m+3)/2 such that (m-1)/2 is an even squarefree number. Cf. A350777. - _Max Alekseyev_, Jul 21 2024 %C A039777 a(1)=2 is the only even term below 10^100000. - _Max Alekseyev_, Jul 22 2024 %e A039777 21 is a term since 21-1 = 2^2*5^1 and (2*5)+(2*1) = 12 = phi(21). %Y A039777 Cf. A000010, A039696, A350777. %K A039777 nonn,more,hard %O A039777 1,1 %A A039777 _Olivier Gérard_ %E A039777 More terms from _Jud McCranie_ %E A039777 Corrected example and a(11)-a(14) from _Donovan Johnson_, Nov 14 2010 %E A039777 a(15)-a(17) from _Max Alekseyev_, Jul 21 2024