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A327875 Numbers k such that s(k) = s(k+1) where s(k) is the sum of unitary, squarefree divisors of k, including 1 (A092261).

%I A327875 #10 Mar 26 2021 08:39:18
%S A327875 8,14,288,675,735,957,1334,1634,2685,2871,5750,8055,9800,12104,12167,
%T A327875 20145,33998,42818,71994,74918,79826,79833,84134,111506,122073,138237,
%U A327875 144990,147454,166934,201597,235224,274533,289454,324423,332928,347738,383594,400315
%N A327875 Numbers k such that s(k) = s(k+1) where s(k) is the sum of unitary, squarefree divisors of k, including 1 (A092261).
%H A327875 Amiram Eldar, <a href="/A327875/b327875.txt">Table of n, a(n) for n = 1..1000</a>
%F A327875 8 is in the sequence since A092261(8) = A092261(9) = 1.
%t A327875 f[p_, e_] := If[e==1, p+1, 1]; s[n_] := Times @@ f @@@ FactorInteger[n]; s1=0; seq = {}; Do[s2 = s[n]; If[s1 == s2, AppendTo[seq, n-1]]; s1 = s2, {n,1,10000}]; seq
%o A327875 (PARI) s(n)={sumdiv(n, d, d*issquarefree(d)*(gcd(d, n/d) == 1))}
%o A327875 { for(k=1, 10^6, if(s(k)==s(k+1), print1(k, ", "))) } \\ _Andrew Howroyd_, Sep 28 2019
%Y A327875 Cf. A002961, A064115, A064125, A092261, A164522, A164557, A293183, A306985, A324295, A325175.
%K A327875 nonn
%O A327875 1,1
%A A327875 _Amiram Eldar_, Sep 28 2019