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A175761 Odd nonprimes such that the arithmetic mean of all prime factors is not an integer. 1
1, 45, 63, 75, 99, 117, 135, 147, 153, 165, 171, 175, 207, 245, 255, 261, 273, 279, 315, 325, 333, 345, 351, 363, 369, 375, 385, 387, 399, 405, 423, 435, 455, 459, 475, 477, 495, 507, 531, 539, 549, 561, 567, 595, 603, 615, 639, 651, 657, 665, 675, 705, 711, 715, 735 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

The presence of 1 (which has no prime factors) is for compatibility with A175352.

LINKS

G. C. Greubel, Table of n, a(n) for n = 1..5000

FORMULA

Equals: Intersection of A175352 and A014076.

EXAMPLE

a(6) = 117 because 117 = 3*3*13 and (3 + 3 + 13)/3 is not an integer.

MATHEMATICA

fQ[n_] := Block[{fi = Flatten[ Table[ #[[1]], {#[[2]]}] & /@ FactorInteger@ n]}, len = Length@ fi; len != 1 && ! IntegerQ[ Plus @@ fi/len]]; Join[{1}, Select[1 + 2 Range@ 356, fQ]] (* Robert G. Wilson v, Aug 31 2010 *)

CROSSREFS

Cf. A141468, A175352.

Sequence in context: A242264 A077646 A230577 * A046364 A321498 A051773

Adjacent sequences:  A175758 A175759 A175760 * A175762 A175763 A175764

KEYWORD

nonn,easy

AUTHOR

Juri-Stepan Gerasimov, Aug 29 2010

EXTENSIONS

Corrected (315, 345 inserted, 355 removed) by R. J. Mathar, Aug 30 2010

STATUS

approved

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Last modified December 10 04:15 EST 2019. Contains 329885 sequences. (Running on oeis4.)