A078578 - OEIS

%I #8 Nov 03 2019 06:47:16

%S 2,2,4,6,8,12,16,24,32,36,44,40,48,64,60,72,64,72,92,96,112,96,144,

%T 120,168,144,160,204,212,160,216,272,264,240,252,256,336,240,348,288,

%U 384,320,420,336,360,320,384,440,432,480,528,432,552,564,480,592,576,624

%N Euler's totient of the average of n-th twin prime pair.

%H Amiram Eldar, <a href="/A078578/b078578.txt">Table of n, a(n) for n = 1..10000</a>

%F a(n) = A000010(A014574(n)).

%t midQ[n_] := PrimeQ[n-1] && PrimeQ[n+1]; EulerPhi[Select[Range[2000], midQ]] (* _Amiram Eldar_, Nov 03 2019 *)

%Y Cf. A000010, A014574.

%K nonn

%O 1,1

%A _Reinhard Zumkeller_, Nov 29 2002