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%I #12 Dec 08 2016 20:02:32
%S 1,4,6,8,27,125,16,12,18,20,28,50,63,32,44,98,52,24,68,42,242,40,70,
%T 338,54,36,56,116,78,578,165,130,722,135,48,164,114,1058,104,188,285,
%U 138,100,80,230,1682,136,128,60,1922,244,152,741,112,225,351,72,284,2738,90,84,651,222,3362,711,332,3698,459,196,96,162,356
%N a(n) = smallest k with sigma(k) + phi(k) - 2k = A278373(n).
%H David W. Wilson, <a href="/A278374/b278374.txt">Table of n, a(n) for n = 1..10000</a>
%H n = 24 is the smallest number with sigma(n) + phi(n) - 2n = 20 = A278383(18), so a(18) = 24.
%t Function[w, Map[Position[w, #][[1, 1]] &, Take[#, 72]] &@ Union@ w]@ Table[DivisorSigma[1, n] + EulerPhi@ n - 2 n, {n, 10^4}] (* _Michael De Vlieger_, Nov 30 2016 *)
%Y Cf. A000010 (phi), A000203 (sigma).
%K nonn
%O 1,2
%A _David W. Wilson_, Nov 19 2016