The On-Line Encyclopedia of Integer Sequences (OEIS)

Revision History for A180164 (Bold, blue-underlined text is an addition; faded, red-underlined text is a ~~deletion~~.)
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A180164

The sum of the two numbers in an amicable pair, A002025(n) + A002046(n).
(history; published version)

#15 by Michel Marcus at Mon Feb 02 03:41:29 EST 2015

LINKS

Eric W. Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/PairSum.html">Pair Sum</a>.

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Mon Feb 02

03:41

Michel Marcus: added link

#14 by Jon E. Schoenfield at Sat Jan 31 22:32:02 EST 2015

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#13 by Jon E. Schoenfield at Sat Jan 31 22:32:01 EST 2015

COMMENTS

Duplicates occur, e.g. , a(32)=a(35)=1296000. - Jeppe Stig Nielsen, Jan 27 2015

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#12 by Michel Marcus at Sat Jan 31 07:29:43 EST 2015

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#11 by Michel Marcus at Sat Jan 31 07:26:27 EST 2015

COMMENTS

It is not known if a(n) is always even (see Hagis links). - Jeppe Stig Nielsen, Jan 31 2015

LINKS

Peter Hagis, <a href="http://dx.doi.org/10.1090/S0025-5718-1970-0276167-4">Lower bounds for relatively prime amicable numbers of opposite parity</a>, Math. Comp. 24 (1970), 963-968.

Peter Hagis, <a href="http://www.jstor.org/stable/2688105">Relatively Prime Amicable Numbers of Opposite Parity</a>, Mathematics Magazine, Vol. 43, No. 1 (Jan., 1970), pp. 14-20.

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Sat Jan 31

07:29

Michel Marcus: added links

#10 by Jeppe Stig Nielsen at Sat Jan 31 04:30:17 EST 2015

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#9 by Jeppe Stig Nielsen at Sat Jan 31 04:29:22 EST 2015

COMMENTS

It is not known if a(n) is always even. - Jeppe Stig Nielsen, Jan 31 2015

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#8 by Michel Marcus at Thu Jan 29 03:42:37 EST 2015

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Discussion

Thu Jan 29

11:28

Jeppe Stig Nielsen: Thank you for pointing that out. I may be missing that dash elsewhere. Will fix.

#7 by Michel Marcus at Thu Jan 29 03:42:18 EST 2015

COMMENTS

This sequence is sorted by the smaller (abundant) member from A002025, so a(n) is not increasing. _- _Jeppe Stig Nielsen_, Jan 27 2015

Duplicates occur, e.g. a(32)=a(35)=1296000. _- _Jeppe Stig Nielsen_, Jan 27 2015

Comment originally by M. F. Hasler, Dec 14 2013, in A161005: "Also: The common value of sigma(a) = sigma(b) of the amicable pairs (a,b). See A137231 for the analog for amicable triples, and A116148 for quadruples." _- _Jeppe Stig Nielsen_, Jan 27 2015

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Thu Jan 29

03:42

Michel Marcus: fixed attributionssss

#6 by Jeppe Stig Nielsen at Tue Jan 27 13:19:29 EST 2015

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Tue Jan 27

14:18

Michel Marcus: Attributions are not ok
see http://oeis.org/wiki/Style_Sheet#Signing_your_name_when_you_contribute_to_an_existing_sequence 
examples 1 and 2

15:44

Jeppe Stig Nielsen: Michel, are you aware that I tried to move a comment by another user, from another entry to here?

16:18

Michel Marcus: Example 1: The fraction of 0's in the first n terms approaches 1/phi. - _N. J. A. Sloane_, Sep 24 2007 
Do you see the - between the period and the _ ?