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Search: id:A008847
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| A008847 |
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Sum of divisors of n^2 is a square. |
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+0
8
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| 1, 9, 20, 180, 1306, 1910, 11754, 17190, 32486, 38423, 47576, 48202, 50920, 51590, 83884, 104855, 132682, 198534, 247863, 292374, 300876, 312374, 313929, 334330, 345807, 376095, 428184, 433818, 458280, 464310, 469623, 498892, 623615, 754956, 768460, 787127, 943695, 985369
(list; graph; listen)
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OFFSET
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1,2
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REFERENCES
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A. H. Beiler, Recreations in the Theory of Numbers, Dover, NY, 1964, p. 10.
I. Kaplansky, The challenges of Fermat, Wallis and Ozanam (and several related challenges): II. Fermat's second challenge, Preprint, 2002.
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MAPLE
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with(numtheory): readlib(issqr): for i from 1 to 10^5 do if issqr(sigma(i^2)) then print(i); fi; od;
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CROSSREFS
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Cf. A008848, A008849, A008850.
Sequence in context: A013573 A146388 A013338 this_sequence A143243 A157812 A161326
Adjacent sequences: A008844 A008845 A008846 this_sequence A008848 A008849 A008850
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KEYWORD
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nonn,nice,easy
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AUTHOR
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N. J. A. Sloane (njas(AT)research.att.com).
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