%I A066172
%S A066172 5,7,33,135,231,273,435,465,824,6375,17115,33704,86355,207315,469395,
%T A066172 603585
%N A066172 Numbers n such that EulerPhi(n+1) - EulerPhi(n) = -d(n).
%C A066172 These are the n at which EulerPhi(n) is decreasing at a rate equal to 
               d(n).
%e A066172 EulerPhi(6) - EulerPhi(5) = 2 - 4 = -2 = -d(5).
%t A066172 Select[ Range[ 1, 10^6 ], EulerPhi[ # ] - EulerPhi[ # + 1 ] == DivisorSigma[ 
               0, # ] & ]
%Y A066172 Sequence in context: A153414 A104815 A007911 this_sequence A018353 A081851 
               A006067
%Y A066172 Adjacent sequences: A066169 A066170 A066171 this_sequence A066173 A066174 
               A066175
%K A066172 nonn
%O A066172 1,1
%A A066172 Joseph L. Pe (joseph_l_pe(AT)hotmail.com), Dec 14 2001