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A179670
Numbers of the form p^3*q*r*s where p, q, r, and s are distinct primes.
12
840, 1320, 1560, 1848, 1890, 2040, 2184, 2280, 2760, 2856, 2970, 3080, 3192, 3432, 3480, 3510, 3640, 3720, 3864, 4158, 4440, 4488, 4590, 4760, 4872, 4914, 4920, 5016, 5130, 5160, 5208, 5250, 5304, 5320, 5640, 5720, 5928, 6072, 6210, 6216, 6360, 6426
OFFSET
1,1
COMMENTS
A050326(a(n)) = 7. - Reinhard Zumkeller, May 03 2013
MATHEMATICA
f[n_]:=Sort[Last/@FactorInteger[n]]=={1, 1, 1, 3}; Select[Range[10000], f]
Take[#[[1]]^3 #[[2]]#[[3]]#[[4]]&/@Flatten[Permutations/@Subsets[Prime[ Range[20]], {4}], 1]//Union, 50] (* Harvey P. Dale, May 16 2021 *)
PROG
(PARI) list(lim)=my(v=List(), t1, t2, t3); forprime(p=2, sqrtnint(lim\30, 3), t1=p^3; forprime(q=2, lim\(6*t1), if(q==p, next); t2=q*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: A068546 A033269 A272595 * A092002 A169827 A158402
KEYWORD
nonn
AUTHOR
STATUS
approved