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Search: id:A064498
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| A064498 |
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Sum of unitary divisors of n^2 is a square. |
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+0
1
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| 1, 42, 120, 156, 246, 287, 1434, 1673, 2016, 5256, 9799, 11808, 18330, 19740, 21385, 34440, 39990, 44772, 45990, 46655, 57270, 60156, 66815, 68832, 102648, 115620, 125255, 149472, 156570, 170820, 182665, 195510, 200760, 208182, 223944, 224196
(list; graph; listen)
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OFFSET
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1,2
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LINKS
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Harry J. Smith, Table of n, a(n) for n=1,...,100
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PROGRAM
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(PARI) {usigma(n, s=1, fac, i)= fac=factor(n); for(i=1, matsize(fac)[1], s=s*(1+fac[i, 1]^fac[i, 2]); ); return(s); } for(n=1, 10^6, if(issquare(usigma(n^2)), print1(n, " ")))
(PARI) usigma(n)= { local(f, s=1); f=factor(n); for(i=1, matsize(f)[1], s*=1 + f[i, 1]^f[i, 2]); return(s) } { n=0; for (m=1, 10^9, if (issquare(usigma(m^2)), write("b064498.txt", n++, " ", m); if (n==100, break)) ) } [From Harry J. Smith (hjsmithh(AT)sbcglobal.net), Sep 16 2009]
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CROSSREFS
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Cf. A034448.
Sequence in context: A044229 A044610 A128674 this_sequence A113518 A044293 A044674
Adjacent sequences: A064495 A064496 A064497 this_sequence A064499 A064500 A064501
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KEYWORD
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easy,nonn
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AUTHOR
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Jason Earls (zevi_35711(AT)yahoo.com), Oct 05 2001
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