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A189989 Numbers with prime factorization pqrs^2t^2. 1
13860, 16380, 21420, 23100, 23940, 25740, 27300, 28980, 32340, 33660, 34650, 35700, 36036, 36540, 37620, 38220, 39060, 39780, 39900, 40950, 42900, 44460, 45540, 46620, 47124, 48300, 48510, 49980, 50820, 51660, 52668, 53550, 53820, 54180 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

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

Will Nicholes, Prime Signatures

Index to sequences related to prime signature

MATHEMATICA

f[n_]:=Sort[Last/@FactorInteger[n]]=={1, 1, 1, 2, 2}; Select[Range[200000], f]

PROG

(PARI) list(lim)=my(v=List(), t1, t2, t3, t4); forprime(p=2, sqrtint(lim\420), t1=p^2; forprime(q=2, sqrtint(lim\(30*t1)), if(q==p, next); t2=q^2*t1; forprime(r=2, lim\(6*t2), if(r==p || r==q, next); t3=r*t2; forprime(s=2, lim\(2*t3), if(s==p || s==q || s==r, next); t4=s*t3; forprime(t=2, lim\t4, if(t==p || t==q || t==r || t==s, next); listput(v, t4*t)))))); Set(v) \\ Charles R Greathouse IV, Aug 25 2016

CROSSREFS

Cf. A179700, A189984, A189985.

Sequence in context: A151642 A235004 A263976 * A069302 A109483 A237941

Adjacent sequences:  A189986 A189987 A189988 * A189990 A189991 A189992

KEYWORD

nonn

AUTHOR

Vladimir Joseph Stephan Orlovsky, May 03 2011

STATUS

approved

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Last modified June 15 22:06 EDT 2021. Contains 345053 sequences. (Running on oeis4.)