A078579 Squarefree kernel of the average of n-th twin prime pair.

2, 6, 6, 6, 30, 42, 30, 6, 102, 6, 138, 30, 30, 6, 66, 114, 30, 30, 282, 78, 174, 210, 6, 462, 174, 570, 30, 618, 642, 330, 30, 822, 138, 858, 42, 510, 258, 210, 354, 546, 6, 1230, 426, 1290, 1302, 330, 714, 66, 1482, 186, 402, 30, 834, 1698, 1722, 894, 78

Offset: 1

Author

Reinhard Zumkeller, Nov 29 2002

Keywords

• nonn

Links

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

Crossrefs

Cf. A007947, A014574, A070195, A078580.

Programs

Mathematica

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

Formula

a(n) = A007947(A014574(n)).

a(A070195(n)) = A070195(n).