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A078576 Sum of distinct prime factors of the average of n-th twin prime pair. 3
2, 5, 5, 5, 10, 12, 10, 5, 22, 5, 28, 10, 10, 5, 16, 24, 10, 10, 52, 18, 34, 17, 5, 23, 34, 29, 10, 108, 112, 21, 10, 142, 28, 29, 12, 27, 48, 17, 64, 25, 5, 51, 76, 53, 43, 21, 29, 16, 37, 36, 72, 10, 144, 288, 53, 154, 18, 318, 35, 23, 42, 18, 352, 34, 16, 81, 29, 378, 12 (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) = A008472(A014574(n)).

EXAMPLE

12th twin prime pair = (A001359(12), A006512(12)) = (149,151), hence A014574(12) = 150 = 2*3*5*5, therefore a(12) = 2+3+5 = 10.

MATHEMATICA

midQ[n_] := PrimeQ[n-1] && PrimeQ[n+1]; f[n_] := Plus @@ FactorInteger[n][[;; , 1]]; f /@ Select[Range[3000], midQ] (* Amiram Eldar, Nov 03 2019 *)

CROSSREFS

Cf. A008472, A014574, A078577, A078575, A078570.

Sequence in context: A171438 A200683 A286541 * A256302 A205396 A082086

Adjacent sequences:  A078573 A078574 A078575 * A078577 A078578 A078579

KEYWORD

nonn

AUTHOR

Reinhard Zumkeller, Nov 29 2002

STATUS

approved

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Last modified April 16 05:26 EDT 2021. Contains 343030 sequences. (Running on oeis4.)