A078578 Euler's totient of the average of n-th twin prime pair.

2, 2, 4, 6, 8, 12, 16, 24, 32, 36, 44, 40, 48, 64, 60, 72, 64, 72, 92, 96, 112, 96, 144, 120, 168, 144, 160, 204, 212, 160, 216, 272, 264, 240, 252, 256, 336, 240, 348, 288, 384, 320, 420, 336, 360, 320, 384, 440, 432, 480, 528, 432, 552, 564, 480, 592, 576, 624

Offset

1,1

Links

Amiram Eldar, Table of n, a(n) for n = 1..10000

Formula

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

Mathematica

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

Crossrefs

Cf. A000010, A014574.

Sequence in context: A210030 A080054 A108494 * A323446 A018129 A361298

Adjacent sequences: A078575 A078576 A078577 * A078579 A078580 A078581

Keyword

nonn

Author

Reinhard Zumkeller, Nov 29 2002

Status

approved