The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.



(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A190294 Numbers with prime factorization pqr^3s^4. 3


%S 15120,22680,23760,28080,33264,35640,36720,39312,41040,42000,42120,

%T 49680,49896,51408,55080,57456,58968,61560,61776,62640,66000,66960,

%U 69552,74520,77112,78000,79920,80784,82320,86184,87696,88560,90288,92664

%N Numbers with prime factorization pqr^3s^4.

%H T. D. Noe, <a href="/A190294/b190294.txt">Table of n, a(n) for n = 1..1000</a>

%H Will Nicholes,<a href="http://willnicholes.com/math/primesiglist.htm">Prime Signatures</a>

%t f[n_]:=Sort[Last/@FactorInteger[n]]=={1,1,3,4};Select[Range[150000],f]

%o (PARI) list(lim)=my(v=List(),t1,t2,t3); forprime(p=2,sqrtnint(lim\120, 4), t1=p^4; forprime(q=2,sqrtnint(lim\(6*t1), 3), if(q==p, next); t2=q^3*t1; forprime(r=2,lim\(2*t2), if(r==p || r==q, next); t3=r*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

%Y Cf. A190292, A190293.

%K nonn

%O 1,1

%A _Vladimir Joseph Stephan Orlovsky_, May 07 2011

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified September 29 04:57 EDT 2020. Contains 337420 sequences. (Running on oeis4.)