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A188483 Numbers whose squares have an odd square abundance 0
742, 3878, 7574, 16058, 2155174, 17886218, 312562708, 599256826, 5015867878, 6305036122, 7661332826 (list; graph; refs; listen; history; text; internal format)
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

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Last modified August 15 16:57 EDT 2022. Contains 356148 sequences. (Running on oeis4.)