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%I A122839 #20 Dec 11 2019 05:05:13
%S A122839 1,2,3,6,14,15,30,35,42,60,70,78,105,190,210,312,357,418,570,714,910,
%T A122839 1045,1254,1428,2090,2730,3135,3640,4522,4674,5278,6270,10659,10920,
%U A122839 12441,13566,14630,15834,16770,18696,20026,21318,23374,24871,24882,24969,25070,25714,27170
%N A122839 Numbers such that Sigma(m)*UnitarySigma(m)= k*UnitaryPhi(m)^2, for some integer k.
%C A122839 Terms which are squarefree appear on A121556.
%H A122839 Amiram Eldar, <a href="/A122839/b122839.txt">Table of n, a(n) for n = 1..1000</a>
%p A122839 isA122839 := proc(m)
%p A122839     A047994(m) ;
%p A122839     modp(numtheory[sigma](m)*A034448(m),%^2) = 0 ;
%p A122839 end proc:
%p A122839 for m from 1 do
%p A122839     if isA122839(m) then
%p A122839         printf("%a,\n", m) ;
%p A122839     end if;
%p A122839 end do: # _R. J. Mathar_, Sep 04 2018
%t A122839 f[p_, e_] := (p^(e+1)-1)*(p^e+1)/(p-1)/(p^e-1)^2; seqQ[1] = True; seqQ[n_] := IntegerQ [Times @@ (f @@@ FactorInteger[n])]; Select[Range[27170], seqQ] (* _Amiram Eldar_, Dec 11 2019 *)
%o A122839 (PARI) isok(m) = ((sigma(m)*usigma(m)) % uphi(m)^2) == 0; \\ _Michel Marcus_, Jan 24 2019
%Y A122839 Cf. A000203, A034448, A047994, A121556.
%K A122839 nonn
%O A122839 1,2
%A A122839 _Yasutoshi Kohmoto_, Oct 23 2006
%E A122839 More terms from _Michel Marcus_, Jan 24 2019

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