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Search: id:A064499
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| A064499 |
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Composite numbers n such that product of aliquot divisors of n is a perfect square. |
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+0
1
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| 12, 16, 18, 20, 28, 32, 44, 45, 48, 50, 52, 63, 68, 75, 76, 80, 81, 92, 98, 99, 112, 116, 117, 124, 147, 148, 153, 162, 164, 171, 172, 175, 176, 180, 188, 192, 207, 208, 212, 236, 242, 243, 244, 245, 252, 256, 261, 268, 272, 275, 279, 284, 288, 292, 300, 304
(list; graph; listen)
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OFFSET
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1,1
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LINKS
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Harry J. Smith, Table of n, a(n) for n=1,...,1000
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MATHEMATICA
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Do[ If[ !PrimeQ[n] && IntegerQ[ Sqrt[ Apply[ Times, Delete[ Divisors[n], -1]]]], Print[n]], {n, 2, 500} ]
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PROGRAM
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(PARI) pad(n)= { local(d, p=1); d=divisors(n); for (i=1, length(d) - 1, p*=d[i]); return(p) } { n=0; for (m=2, 10^9, if (!isprime(m) && issquare(pad(m)), write("b064499.txt", n++, " ", m); if (n==1000, break)) ) } [From Harry J. Smith (hjsmithh(AT)sbcglobal.net), Sep 16 2009]
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CROSSREFS
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Cf. A048699.
Sequence in context: A126763 A058080 A119911 this_sequence A080258 A054290 A107308
Adjacent sequences: A064496 A064497 A064498 this_sequence A064500 A064501 A064502
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KEYWORD
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base,easy,nonn
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AUTHOR
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Robert G. Wilson v (rgwv(AT)rgwv.com), Oct 05 2001
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