A189344 Numbers with prime factorization pq^2r^2s^2.

6300, 8820, 9900, 11700, 14700, 15300, 17100, 19404, 20700, 21780, 22050, 22932, 26100, 27900, 29988, 30420, 30492, 33300, 33516, 36300, 36900, 38700, 40572, 42300, 42588, 47700, 50700, 51156, 52020, 53100, 53900, 54450, 54684, 54900

Offset: 1

Author

Vladimir Joseph Stephan Orlovsky, May 09 2011

Keywords

• nonn

Links

• T. D. Noe, Table of n, a(n) for n = 1..1000
• Will Nicholes, Prime Signatures
• Index to sequences related to prime signature

Crossrefs

Cf. A179688, A179693, A179700.

Programs

Mathematica

f[n_]:=Sort[Last/@FactorInteger[n]]=={1,2,2,2}; Select[Range[90000],f]

PARI

list(lim)=my(v=List(),t1,t2,t3); forprime(p=2,sqrtint(lim\180), t1=p^2; forprime(q=2,sqrtint(lim\(12*t1)), if(q==p, next); t2=q^2*t1; forprime(r=2,sqrtint(lim\(2*t2)), if(r==p || r==q, next); t3=r^2*t2; forprime(s=2,lim\t3, if(s==p || s==q || s==r, next); listput(v, t3*s))))); Set(v) \\ Charles R Greathouse IV, Aug 25 2016