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 A349308 #9 Nov 14 2021 07:48:14 %S A349308 80,135,296,343,375,624,728,1160,1431,1592,1624,2240,2295,2456,2511, %T A349308 2624,2727,2888,3429,3591,3624,3752,3992,4023,4184,4671,4887,4913, %U A349308 5048,5144,5264,5319,5480,5696,6183,6344,6375,6591,6615,6776,6858,6859,7479,7624,7640 %N A349308 Numbers k such that A321167(k) = A321167(k+1) > 1. %C A349308 Without the restriction that A321167(k) > 1, all the terms of A340152 would be in this sequence. %C A349308 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 6858, 13375, 22625, ... %H A349308 Amiram Eldar, <a href="/A349308/b349308.txt">Table of n, a(n) for n = 1..10000</a> %e A349308 80 is a term since A321167(80) = A321167(81) = 3. %t A349308 f[p_, e_] := p^e - 1; uphi[1] = 1; uphi[n_] := Times @@ f @@@ FactorInteger[n]; fe[p_, e_] := uphi[e]; euphi[n_] := Times @@ fe @@@ FactorInteger[n]; Select[Range[8000], euphi[#] == euphi[# + 1] > 1 &] %Y A349308 Cf. A321167, A340152. %Y A349308 Subsequence of A068140. %Y A349308 Similar sequences: A001274, A287055, A293184, A326403, A349307. %K A349308 nonn %O A349308 1,1 %A A349308 _Amiram Eldar_, Nov 14 2021