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A110108 Conjectured values of n such that sigma(n)+sigma(k)=sigma(n+k) has no solution. 1
3, 9, 15, 21, 27, 39, 57, 63, 81, 93, 105, 117, 165, 171, 183, 189, 201, 219, 225, 243, 256, 279, 303, 309, 333, 351, 363, 375, 381, 387, 405, 417, 441, 453, 471, 489, 512, 543, 549, 567, 579, 603, 633, 651, 657, 669, 687, 693, 723, 729, 741, 777 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

All k<10^10 have been checked. Note that this sequence appears to contain all powers of 3. It also contains 256 and 512, which are the only even numbers listed here.

All k<10^11 have been checked. 65 n values remain < 1000. - Donovan Johnson, Aug 29 2012

REFERENCES

R. K. Guy, Unsolved Problems in Number Theory, 3rd Ed., New York, Springer-Verlag, 2004, Section B15.

LINKS

Table of n, a(n) for n=1..52.

CROSSREFS

Cf. A066435 (least k such that sigma(n)+sigma(k)=sigma(n+k)).

Sequence in context: A228935 A016945 A222640 * A162843 A102954 A272749

Adjacent sequences:  A110105 A110106 A110107 * A110109 A110110 A110111

KEYWORD

nonn

AUTHOR

T. D. Noe, Jul 12 2005

EXTENSIONS

Two terms removed (465 and 711) by Donovan Johnson, Aug 29 2012

STATUS

approved

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Last modified October 22 21:09 EDT 2018. Contains 316505 sequences. (Running on oeis4.)