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A002046
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Larger of amicable pair.
(Formerly M5435 N2363)
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20
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284, 1210, 2924, 5564, 6368, 10856, 14595, 18416, 76084, 66992, 71145, 87633, 88730, 124155, 139815, 123152, 153176, 168730, 176336, 180848, 203432, 202444, 365084, 389924, 430402, 399592, 455344, 486178, 514736, 525915, 669688, 686072
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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COMMENTS
| The elements 76084, 123152, etc. are intentionally out of numerical order so that a(n) and A002025(n) form amicable pairs. [From Michael B. Porter (michael_b_porter(AT)yahoo.com), Apr 17 2010]
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REFERENCES
| N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
For additional references see A002025.
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LINKS
| T. D. Noe, Table of n, a(n) for n=1..39374 (terms such that smaller number A002025(n) is < 10^14)
J. Bell, A translation of Leonhard Euler's...
M. Garcia, A Million New Amicable Pairs, J. Integer Seqs., Vol. 4 (2001), #01.2.6.
S. S. Gupta, Amicable Numbers
Hisanori Mishima, First 236 amicable pairs
D. Moews, Perfect, amicable and sociable numbers
J. O. M. Pedersen, Known Amicable Pairs
J. O. M. Pedersen, Tables of Aliquot Cycles
T. Trotter, Jr., Amicable Numbers
Eric Weisstein's World of Mathematics, Link to a section of The World of Mathematics.
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MATHEMATICA
| amicableQ[n_] := With[{s = DivisorSigma[1, n] - n}, r = n != s && n == DivisorSigma[1, s] - s; If[r, mate[n] = s; True, False]]; mate /@ Select[ Range[lim], amicableQ[#] && # < mate[#] &] (* From Jean-François Alcover, Sep 20 2011 *)
Table[DivisorSigma[1, A002025[n]] - A002025[n], {n, 50}] (* T. D. Noe, Sep 20 2011 *)
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PROG
| Contribution from Michael B. Porter (michael_b_porter(AT)yahoo.com), Apr 17 2010: (Start)
(PARI) aliquot(n)=sigma(n)-n
isA002046(n)={local(a); a=aliquot(n); a<n && aliquot(a)==n} (End)
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CROSSREFS
| Cf. A002025, A063990.
Sequence in context: A061310 A092681 A090789 * A143191 A180220 A108110
Adjacent sequences: A002043 A002044 A002045 * A002047 A002048 A002049
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KEYWORD
| nonn,nice
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AUTHOR
| N. J. A. Sloane (njas(AT)research.att.com).
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EXTENSIONS
| More terms from Larry Reeves (larryr(AT)acm.org), Oct 25 2000
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