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%I #13 Dec 11 2019 05:05:05
%S 1,2,3,6,14,15,30,35,42,70,78,105,190,210,348,357,418,570,714,910,
%T 1045,1144,1254,2090,2296,2730,3135,3432,4060,4522,4674,5278,6270,
%U 6888,10168,10659,10824,12180,12441,13566,14630,15834,16770,17160
%N Numbers such that sigma(n)^2 is divisible by UnitarySigma(n)*UnitaryPhi(n).
%H Donovan Johnson, <a href="/A121556/b121556.txt">Table of n, a(n) for n = 1..1000</a>
%p for n from 1 to 20000 do if numtheory[sigma](n)^2 mod (A047994(n)*A034448(n)) = 0 then printf("%d,",n) ; end if;end do:
%t f[p_, e_] := (p^(e+1)-1)^2/(p-1)^2/(p^(2*e)-1); seqQ[1] = True; seqQ[n_] := IntegerQ [Times @@ (f @@@ FactorInteger[n])]; Select[Range[17160], seqQ] (* _Amiram Eldar_, Dec 11 2019 *)
%Y Cf. A000203, A121647, A078557, A020492, A034448, A047994.
%K nonn
%O 1,2
%A _Yasutoshi Kohmoto_, Sep 12 2006
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