A078577 Sum of all prime factors of the average of n-th twin prime pair.

4, 5, 7, 8, 10, 12, 12, 12, 22, 13, 28, 15, 15, 15, 19, 26, 16, 16, 52, 22, 36, 19, 17, 23, 37, 29, 19, 108, 112, 23, 19, 142, 33, 29, 22, 29, 52, 22, 67, 27, 20, 51, 79, 53, 43, 25, 31, 29, 37, 42, 76, 21, 146, 288, 53, 156, 27, 318, 37, 28, 48, 33, 352, 41, 26, 81, 32

Offset

1,1

Links

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

Formula

a(n) = A001414(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+5 = 15.

Mathematica

midQ[n_] := PrimeQ[n-1] && PrimeQ[n+1]; f[n_] := Plus @@ Times @@@ FactorInteger[n]; f /@ Select[Range[2500], midQ] (* Amiram Eldar, Nov 03 2019 *)

Crossrefs

Cf. A001414, A014574, A078576, A078575, A078571.

Sequence in context: A202186 A247467 A032728 * A225387 A037259 A219115

Adjacent sequences: A078574 A078575 A078576 * A078578 A078579 A078580

Keyword

nonn

Author

Reinhard Zumkeller, Nov 29 2002

Status

approved