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