

A188483


Numbers whose squares have an odd square abundance


0



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



