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A190107 Numbers with prime factorization pqr^2s^4. 5
5040, 7920, 8400, 9360, 11088, 11340, 11760, 12240, 13104, 13200, 13680, 15600, 16560, 17136, 17820, 19152, 20400, 20592, 20880, 21060, 22320, 22800, 23184, 24948, 25872, 26640, 26928, 27540, 27600, 28350, 29040, 29232, 29484, 29520 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
A050326(a(n)) = 3. - Reinhard Zumkeller, May 03 2013
LINKS
Will Nicholes, Prime Signatures
MATHEMATICA
f[n_]:=Sort[Last/@FactorInteger[n]]=={1, 1, 2, 4}; Select[Range[60000], f]
PROG
(PARI) list(lim)=my(v=List(), t1, t2, t3); forprime(p=2, sqrtnint(lim\60, 4), t1=p^4; forprime(q=2, sqrtint(lim\(6*t1)), if(q==p, next); t2=q^2*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
CROSSREFS
Sequence in context: A111030 A068378 A036458 * A090393 A147632 A321843
KEYWORD
nonn
AUTHOR
STATUS
approved

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Last modified March 28 20:05 EDT 2024. Contains 371254 sequences. (Running on oeis4.)