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A188486 Numbers n such that abundance(n) is an odd square. 3
550564, 15038884, 57365476, 197686728, 257859364, 1027291978962, 4644774970276, 319916794343524, 694453849937352, 97695446432293264, 359108743507594276 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Counterexamples to the Kravitz conjecture. Subsequence of A188484 with positive abundances. Abundances are A188488, sigma(n) - 2n.

LINKS

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

Eric Weisstein's World of Mathematics, Kravitz Conjecture

CROSSREFS

Cf. A188484, A188488.

Sequence in context: A251035 A236827 A077456 * A204571 A253614 A249687

Adjacent sequences:  A188483 A188484 A188485 * A188487 A188488 A188489

KEYWORD

nonn,hard

AUTHOR

Eric W. Weisstein, Apr 01 2011

EXTENSIONS

a(4), a(5) from D. S. McNeil, Apr 02 2011

a(6) - a(8) from Jack Brennen, May 03 2011

a(9) from Jack Brennen and Charles R Greathouse IV, May 04 2011

a(10)-a(11) from Charles R Greathouse IV, May 04, 2011

STATUS

approved

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Last modified December 3 08:48 EST 2016. Contains 278698 sequences.