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%I #6 Feb 11 2014 19:05:32
%S 315,351,819,3375,24921,47520,99540,107541,125631,189175,410805,
%T 763665,877365,1680855,2480555,6911079,7849479,9646395,11245365,
%U 12528165,14242800,14684055,16921191,17194365,19395025,27782160,33830685,34823075,36278649,43955955
%N phi(n-1) + phi(n+1) = 1/2 sigma(n).
%e phi(314) + phi(316) = 156 + 156 = 312 = 1/2 sigma(315), so 315 belongs to the sequence.
%t Select[Range[2, 10^5], EulerPhi[ # - 1] + EulerPhi[ # + 1] == (1/2)DivisorSigma[1, # ] &]
%Y Cf. A000010, A000203.
%K nonn
%O 1,1
%A _Joseph L. Pe_, Oct 23 2002
%E a(8)-a(30) from _Donovan Johnson_, Mar 01 2012
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