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 A349307 #10 Nov 14 2021 07:40:23 %S A349307 80,135,296,343,375,567,624,728,783,944,1160,1431,1592,1624,1647,1808, %T A349307 1863,2024,2240,2295,2456,2511,2624,2727,2888,3087,3320,3429,3536, %U A349307 3591,3624,3752,3992,4023,4184,4239,4375,4400,4455,4624,4671,4887,4912,4913,5048,5103 %N A349307 Numbers k such that A072911(k) = A072911(k+1) > 1. %C A349307 Without the restriction that A072911(k) > 1, all the terms of A340152 would be in this sequence. %C A349307 In contrast to A001274, which has only one known pair of consecutive terms (5186 and 5187), this sequence seems to have many pairs of consecutive terms. The smaller members of these pairs are 4912, 5750, 6858, ... %H A349307 Amiram Eldar, <a href="/A349307/b349307.txt">Table of n, a(n) for n = 1..10000</a> %e A349307 80 is a term since A072911(80) = A072911(81) = 2. %t A349307 f[p_, e_] := EulerPhi[e]; ephi[n_] := Times @@ f @@@ FactorInteger[n]; Select[Range[5000], ephi[#] == ephi[# + 1] > 1 &] %Y A349307 Cf. A072911, A340152. %Y A349307 Subsequence of A068140. %Y A349307 Similar sequences: A001274, A287055, A293184, A326403, A349308. %K A349307 nonn %O A349307 1,1 %A A349307 _Amiram Eldar_, Nov 14 2021