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Search: id:A063729
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| A063729 |
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Numbers n such that sigma(n)+1 is a square and sets a new record for such squares. |
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+0
1
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| 2, 7, 8, 14, 32, 54, 60, 72, 84, 120, 196, 252, 312, 378, 512, 540, 860, 990, 1020, 1350, 1488, 1560, 2190, 2232, 3084, 3144, 3288, 3444, 3456, 4620, 7740, 8520, 9720, 13080, 13500, 19230, 19590, 20088, 21120, 27090, 29064, 29232, 31500, 42336
(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,...,150
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PROGRAM
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(PARI) j=[]; for(n=1, 70000, x=sigma(n)+1; if(issquare(x), b=x; if(b>a, a=b; \ j=concat(j, n)))); j
(PARI) { n=0; a=-1; for (m=1, 10^9, if (issquare(b=sigma(m) + 1), if (b>a, a=b; write("b063729.txt", n++, " ", m); if (n==150, break))) ) } [From Harry J. Smith (hjsmithh(AT)sbcglobal.net), Aug 28 2009]
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CROSSREFS
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Cf. A063531.
Sequence in context: A063531 A063771 A064293 this_sequence A023178 A080572 A162664
Adjacent sequences: A063726 A063727 A063728 this_sequence A063730 A063731 A063732
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KEYWORD
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nonn
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AUTHOR
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Jason Earls (zevi_35711(AT)yahoo.com), Aug 12 2001
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