|
| |
|
|
A070006
|
|
Arithmetical mean of distinct primes dividing n is a prime and n is neither a prime nor power of a prime. Subsequence of A070005.
|
|
2
| |
|
|
21, 33, 57, 63, 69, 85, 93, 99, 105, 129, 133, 145, 147, 171, 177, 189, 195, 205, 207, 213, 217, 231, 237, 249, 253, 265, 279, 297, 309, 315, 363, 387, 393, 417, 425, 441, 445, 465, 469, 483, 489, 493, 505, 513, 517, 525, 531, 553, 565, 567, 573, 585, 597
(list; graph; refs; listen; history; internal format)
|
|
|
|
OFFSET
| 1,1
|
|
|
EXAMPLE
| n=993=3.331, mean=334/2=167, a prime
|
|
|
MATHEMATICA
| ffi[x_] := Flatten[FactorInteger[x]] lf[x_] := Length[FactorInteger[x]] ba[x_] := Table[Part[ffi[x], 2*w-1], {w, 1, lf[x]}] Do[s=Apply[Plus, ba[n]]/lf[n]; If[PrimeQ[s]&&Greater[lf[n], 1], Print[n]], {n, 2, 1000}]
|
|
|
CROSSREFS
| Cf. A070005, A008472, A001414.
Sequence in context: A141249 A026068 A176945 * A189986 A190299 A084109
Adjacent sequences: A070003 A070004 A070005 * A070007 A070008 A070009
|
|
|
KEYWORD
| easy,nonn
|
|
|
AUTHOR
| Labos E. (labos(AT)ana.sote.hu), Apr 11 2002
|
| |
|
|
