Search: id:A057654
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%I A057654
%S A057654 1,95,99,146,323,377,1095,1102,1351,1368,1630,1919,1943,2261,2639,2743,
%T A057654 3915,4607,4743,5042,5045,5183,5249,6347,6497,7389,8265,8307,8749,9407,
%U A057654 9701
%N A057654 Numbers n such that sigma(n)^2-phi(n)^2 is a perfect square.
%e A057654 sigma(95)^2-phi(95)^2 = 120^2 - 72^2 = 96^2, so 95 is a term of the sequence.
%t A057654 Select[Range[10^4], IntegerQ[Sqrt[DivisorSigma[1, # ]^2 - EulerPhi[ # 
               ]^2]] &]
%Y A057654 Sequence in context: A033415 A067266 A055467 this_sequence A046005 A045121 
               A057874
%Y A057654 Adjacent sequences: A057651 A057652 A057653 this_sequence A057655 A057656 
               A057657
%K A057654 easy,nonn
%O A057654 1,2
%A A057654 Joseph L. Pe (joseph_l_pe(AT)hotmail.com), Feb 12 2002

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