A163569 Numbers of the form p^3*q^2*r where p, q and r are three distinct primes.

360, 504, 540, 600, 756, 792, 936, 1176, 1188, 1224, 1350, 1368, 1400, 1404, 1500, 1656, 1836, 1960, 2052, 2088, 2200, 2232, 2250, 2484, 2600, 2646, 2664, 2904, 2952, 3096, 3132, 3348, 3384, 3400, 3500, 3800, 3816, 3996, 4056, 4116, 4248, 4312, 4392

Offset

1,1

Comments

There is no constraint on which of the three primes is the largest or smallest.

Subsequence of A137487. - R. J. Mathar, Aug 01 2009

Links

T. D. Noe, Table of n, a(n) for n = 1..1000

Index to sequences related to prime signature

Example

360=2^3*3^2*5. 504=2^3*3^2*7. 1188=2^2*3^3*11.

Mathematica

f[n_]:=Sort[Last/@FactorInteger[n]]=={1, 2, 3}; Select[Range[5000], f]

Prog

(PARI) list(lim)=my(v=List(), t1, t2); forprime(p=2, (lim\12)^(1/3), t1=p^3; forprime(q=2, sqrt(lim\t1), if(p==q, next); t2=t1*q^2; forprime(r=2, lim\t2, if(p==r||q==r, next); listput(v, t2*r)))); vecsort(Vec(v)) \\ Charles R Greathouse IV, Jul 20 2011

Crossrefs

Sequence in context: A060665 A323024 A072414 * A063067 A076205 A048978

Adjacent sequences: A163566 A163567 A163568 * A163570 A163571 A163572

Keyword

nonn

Author

Vladimir Joseph Stephan Orlovsky, Jul 31 2009

Status

approved