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A078578 Euler's totient of the average of n-th twin prime pair. 1
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 (list; graph; refs; listen; history; text; internal format)
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 A091915

Adjacent sequences:  A078575 A078576 A078577 * A078579 A078580 A078581

KEYWORD

nonn

AUTHOR

Reinhard Zumkeller, Nov 29 2002

STATUS

approved

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Last modified March 8 12:56 EST 2021. Contains 341948 sequences. (Running on oeis4.)