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 A078575 Sum of divisors of the average of n-th twin prime pair. 4

%I

%S 7,12,28,39,72,96,168,195,216,280,288,372,546,508,468,560,744,720,576,

%T 840,840,1344,1240,1152,1170,1440,1860,1248,1296,2016,2178,1656,2184,

%U 2016,2223,3024,2640,2976,2340,3136,3315,3024,2808,3168,3072,4320,4032

%N Sum of divisors of the average of n-th twin prime pair.

%H Amiram Eldar, <a href="/A078575/b078575.txt">Table of n, a(n) for n = 1..10000</a>

%F a(n) = A000203(A014574(n)).

%e 4th twin prime pair = (A001359(4), A006512(4)) = (17,19), hence A014574(4) = 18 with divisors = {1,2,3,6,9,18} therefore a(4) = 1+2+3+6+9+18 = 39.

%t midQ[n_] := PrimeQ[n-1] && PrimeQ[n+1]; DivisorSigma[1, Select[Range[1500], midQ]] (* _Amiram Eldar_, Nov 03 2019 *)

%Y Cf. A000203, A014574, A078574, A078576, A078577.

%K nonn

%O 1,1

%A _Reinhard Zumkeller_, Nov 29 2002

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Last modified January 25 09:59 EST 2022. Contains 350565 sequences. (Running on oeis4.)