A188483 Numbers whose squares have an odd square abundance

742, 3878, 7574, 16058, 2155174, 17886218, 312562708, 599256826, 5015867878, 6305036122, 7661332826

Offset

1,1

Comments

Kravitz conjectured that no numbers exist whose abundance is a positive odd square. The squares of this sequence are counterexamples.

a(12) <= 37379475098. a(13) <= 56559884906. - Donovan Johnson, Apr 07 2011

References

Guy, R. K. Unsolved Problems in Number Theory, 3rd ed. New York: Springer-Verlag, 2004, page 74.

Links

Table of n, a(n) for n=1..11.

Eric Weisstein, Kravitz Conjecture

Crossrefs

Cf. A188486

Sequence in context: A319043 A044984 A252576 * A235675 A235445 A349677

Adjacent sequences: A188480 A188481 A188482 * A188484 A188485 A188486

Keyword

nonn,hard,more

Author

Ed Pegg Jr, Apr 01 2011

Extensions

More terms, page number in Guy, cross references.

a(9)-a(11) from Donovan Johnson, Apr 07 2011

Status

approved