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 A348657 #9 Oct 28 2021 10:01:27 %S A348657 266,321,1015,2544,4004,4277,5016,15861,28461,47613,63546,135078, %T A348657 137333,203709,207024,265489,344217,383466,517610,603687,787156, %U A348657 798625,876469,1100835,1713865,2062863,2246923,2349390,2666741,3013830,3961129,5048409,6148960,6491717 %N A348657 Numbers k such that k and k+1 have the same denominator of the harmonic means of their unitary divisors. %C A348657 Numbers k such that A103340(k) = A103340(k+1). %C A348657 The common denominators of k and k+1 are 30, 36, 36, 153, 15, 96, 45, 936, ... %C A348657 Can 3 consecutive numbers have the same denominator of harmonic mean of unitary divisors? There are no such numbers below 2.5*10^10. %H A348657 Amiram Eldar, <a href="/A348657/b348657.txt">Table of n, a(n) for n = 1..400</a> %e A348657 266 is a term since the harmonic means of the unitary divisors of 266 and 267 are 133/30 and 89/30, respectively, and both have the denominator 30. %t A348657 f[p_, e_] := 2/(1 + p^(-e)); d[n_] := Denominator[Times @@ f @@@ FactorInteger[n]]; Select[Range[10^5], d[#] == d[# + 1] &] %Y A348657 The unitary version of A348415. %Y A348657 Cf. A103339, A103340. %K A348657 nonn %O A348657 1,1 %A A348657 _Amiram Eldar_, Oct 28 2021