A078581 Arithmetic derivative of the average of n-th twin prime pair.

4, 5, 16, 21, 31, 41, 92, 156, 91, 216, 121, 185, 336, 640, 249, 316, 608, 459, 241, 596, 476, 704, 1296, 493, 627, 619, 1340, 521, 541, 1072, 1647, 691, 1416, 859, 1281, 1624, 1916, 1445, 1257, 1696, 4800, 1301, 1509, 1363, 1313, 2804, 2192, 2200, 1427

Offset

1,1

Links

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

Formula

a(n) = A003415(A014574(n)).

Mathematica

midQ[n_] := PrimeQ[n-1] && PrimeQ[n+1]; f[n_] := n * Total[#2 / #1 & @@@ FactorInteger[n]]; f /@ Select[Range[1500], midQ] (* Amiram Eldar, Nov 03 2019 *)

Crossrefs

Cf. A003415, A014574, A078579.

Sequence in context: A309759 A025617 A227855 * A092809 A250254 A293344

Adjacent sequences: A078578 A078579 A078580 * A078582 A078583 A078584

Keyword

nonn

Author

Reinhard Zumkeller, Nov 29 2002

Status

approved