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 A093034 #25 May 09 2024 02:53:30 %S A093034 2,7,29,673,30241,523777,2178541,23569921,33550337,66433720321, %T A093034 137438691329,30823866178561,796928461056001,1802582780370364661761, %U A093034 9186050031556349952001,2827987212986831882236723201,630532357710420079508428362350593,1928622300236318049928258133164033 %N A093034 Primes of the form 1 + multiple perfect number. %C A093034 From _M. F. Hasler_ and _Farideh Firoozbakht_, Apr 08 2010: (Start) %C A093034 Theorem: If p is a term of this sequence and p-1 is a t-perfect number then for each positive integer k, x=p^k is a solution to the equation sigma(phi(x)) = t*(x-1). %C A093034 Proof: sigma(phi(x)) = sigma(phi(p^k)) = sigma((p-1)*p^(k-1)) = sigma(p-1)*sigma(p^(k-1)) = t*(p-1)*(p^k-1)/(p-1) = t*(p^k-1) = t*(x-1). (End) %H A093034 Amiram Eldar, <a href="/A093034/b093034.txt">Table of n, a(n) for n = 1..35</a> %Y A093034 Cf. A000010 (phi), A000203 (sigma), A007691, A171263, A171264, A171265. %K A093034 nonn %O A093034 1,1 %A A093034 _Labos Elemer_, May 12 2004 %E A093034 a(11)-a(16) from _Donovan Johnson_, Nov 30 2008 %E A093034 a(17)-a(18) from _Amiram Eldar_, May 09 2024