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%I #6 Jan 22 2018 19:31:02
%S 6,10,12,15,18,22,24,26,28,36,40,46,48,52,58,63,72,80,82,88,96,100,
%T 106,108,112,124,136,148,162,166,172,178,192,196,226,232,242,250,262,
%U 268,285,288,292,316,346,352,358,382,388,400,432,448,466,478,486,502
%N Numbers n such that uphi(n) + usigma(n) = uphi(n+1) + usigma(n+1), where uphi is the unitary totient function (A047994) and usigma the sum of unitary divisors (A034448).
%C The unitary version of A145749.
%e 6 is in the sequence since uphi(6) + usigma(6) = 2 + 12 = uphi(7) + usigma(7) = 6 + 8 = 14.
%t usigma[n_] := If[n == 1, 1, Times @@ (1 + Power @@@ FactorInteger[n])];
%t uphi[n_] := (Times @@ (Table[#[[1]]^#[[2]] - 1, {1}] & /@ FactorInteger[n]))[[1]]; u[n_] := uphi[n]+usigma[n]; aQ[n_] := u[n] == u[n + 1]; Select[Range[10^3], aQ]
%Y Cf. A034448, A047994, A145749.
%K nonn
%O 1,1
%A _Amiram Eldar_, Dec 29 2017
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