A110108 Conjectured values of n such that sigma(n)+sigma(k)=sigma(n+k) has no solution.

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

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