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A078581
Arithmetic derivative of the average of n-th twin prime pair.
1
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
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
KEYWORD
nonn
AUTHOR
Reinhard Zumkeller, Nov 29 2002
STATUS
approved