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A179695 Numbers of the form p^3*q^2*r^2 where p, q, and r are distinct primes. 7
1800, 2700, 3528, 4500, 5292, 8712, 9800, 12168, 12348, 13068, 18252, 20808, 24200, 24500, 25992, 31212, 33075, 33800, 34300, 38088, 38988, 47432, 47916, 55125, 57132, 57800, 60500, 60552, 66248, 69192, 72200, 77175, 79092, 81675, 84500 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

A050326(a(n)) = 5, subsequence of A225228. - Reinhard Zumkeller, May 03 2013

LINKS

T. D. Noe, Table of n, a(n) for n = 1..1000

Will Nicholes, Prime Signatures

Index to sequences related to prime signature

MAPLE

op(select(n->nops(factorset(n))=3 and sort([seq(op(2, a), a=ifactors(n)[2])])=[2, 2, 3], [$1..84500])); # Paolo P. Lava, Jul 18 2019

MATHEMATICA

f[n_]:=Sort[Last/@FactorInteger[n]]=={2, 2, 3}; Select[Range[10^5], f]

f[n_]:={Times@@(n^{2, 2, 3}), Times@@(n^{2, 3, 2}), Times@@(n^{3, 2, 2})}; Module[ {nn=20}, Select[Flatten[f/@Subsets[Prime[Range[nn]], {3}]], #<= 72*Prime[ nn]^2&]]//Union (* Harvey P. Dale, Jul 05 2019 *)

PROG

(PARI) list(lim)=my(v=List(), t1, t2); forprime(p=2, (lim\36)^(1/3), t1=p^3; forprime(q=2, sqrt(lim\t1), if(p==q, next); t2=t1*q^2; forprime(r=q+1, sqrt(lim\t2), if(p==r, next); listput(v, t2*r^2)))); vecsort(Vec(v)) \\ Charles R Greathouse IV, Jul 24 2011

CROSSREFS

Sequence in context: A235898 A035891 A069476 * A025139 A035767 A107563

Adjacent sequences:  A179692 A179693 A179694 * A179696 A179697 A179698

KEYWORD

nonn

AUTHOR

Vladimir Joseph Stephan Orlovsky, Jul 24 2010

STATUS

approved

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Last modified October 15 10:46 EDT 2019. Contains 328026 sequences. (Running on oeis4.)