A067341 - OEIS

A067341

Number of prime factors divided by the number of distinct prime factors is an integer and n is neither squarefree, nor power of prime.

24, 36, 40, 54, 56, 88, 96, 100, 104, 135, 136, 144, 152, 160, 184, 189, 196, 216, 224, 225, 232, 240, 248, 250, 296, 297, 324, 328, 336, 344, 351, 352, 360, 375, 376, 384, 400, 416, 424, 441, 459, 472, 484, 486, 488, 504, 513, 528, 536, 540, 544, 560, 568

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OFFSET

1,1

LINKS

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

FORMULA

A001222(n)/A001221(n) is integer, A001222(n)>A001221(n)>1.

MATHEMATICA

ff[x_] := Flatten[FactorInteger[x]] f1[x_] := Length[FactorInteger[x]] f2[x_] := Apply[Plus, Table[Part[ff[x], 2*w], {w, 1, f1[x]}]] Do[s=f2[n]/f1[n]; If[IntegerQ[s]&&Greater[s, 1]&&Greater[f1[n], 1], Print[n]], {n, 2, 10000}]

PROG

(PARI) is(n)=my(f=factor(n)[, 2]); #f>1 && vecsum(f)%#f==0 && vecmax(f)>1 \\ Charles R Greathouse IV, Oct 15 2015

CROSSREFS

Cf. A001221, A001222, A067340.

Sequence in context: A224907 A292352 A307342 * A307682 A290016 A330880

Adjacent sequences: A067338 A067339 A067340 * A067342 A067343 A067344

KEYWORD

nonn

AUTHOR

Labos Elemer, Jan 16 2002

STATUS

approved