A190319 Numbers with prime factorization pq^2r^2s^4.

25200, 35280, 39600, 46800, 56700, 58800, 61200, 68400, 77616, 79380, 82800, 87120, 89100, 91728, 104400, 105300, 111600, 119952, 121680, 121968, 133200, 134064, 137700, 145200, 147600, 153900, 154800, 157500, 162288, 169200, 170352

Offset: 1

Author

Vladimir Joseph Stephan Orlovsky, May 08 2011

Keywords

• nonn

Links

• T. D. Noe, Table of n, a(n) for n = 1..1000
• Will Nicholes,Prime Signatures

Crossrefs

Cf. A190293, A190294.

Programs

Mathematica

f[n_]:=Sort[Last/@FactorInteger[n]]=={1,2,2,4};Select[Range[250000],f]

PARI

list(lim)=my(v=List(),t1,t2,t3); forprime(p=2,sqrtnint(lim\180, 4), t1=p^4; 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