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 A190377 Numbers with prime factorization p^2q^2r^2s^2 1
 44100, 108900, 152100, 213444, 260100, 298116, 324900, 476100, 509796, 592900, 636804, 736164, 756900, 828100, 864900, 933156, 1232100, 1258884, 1334025, 1416100, 1483524, 1512900, 1572516, 1664100, 1695204, 1758276, 1768900, 1863225 (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 MATHEMATICA f[n_]:=Sort[Last/@FactorInteger[n]]=={2, 2, 2, 2}; Select[Range[3000000], f] PROG (PARI) list(lim)=my(v=List(), t1, t2, t3); forprime(p=2, sqrtint(lim\900), t1=p^2; forprime(q=2, sqrtint(lim\(36*t1)), if(q==p, next); t2=q^2*t1; forprime(r=2, sqrtint(lim\(4*t2)), if(r==p || r==q, next); t3=r^2*t2; forprime(s=2, sqrtint(lim\t3), if(s==p || s==q || s==r, next); listput(v, t3*s^2))))); Set(v) \\ Charles R Greathouse IV, Aug 25 2016 CROSSREFS Cf. A190108, A190109. Sequence in context: A043303 A233790 A223457 * A049205 A234426 A187436 Adjacent sequences:  A190374 A190375 A190376 * A190378 A190379 A190380 KEYWORD nonn AUTHOR Vladimir Joseph Stephan Orlovsky, May 09 2011 STATUS approved

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Last modified August 7 23:53 EDT 2020. Contains 336280 sequences. (Running on oeis4.)