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A191965 A problem of Zarankiewicz: maximal number of 1's in a symmetric n X n matrix of 0's and 1's with 0's on the main diagonal and no "rectangle" with 1's at the four corners. 2
0, 2, 6, 8, 12, 14, 18, 22, 26, 32 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

In other words, the pattern

1...1

.....

1...1

is forbidden.

REFERENCES

D. Bienstock E. Gyori, An extremal problem on sparse 0-1 matrices. SIAM J. Discrete Math. 4 (1991), 17-27.

B. Bollobas, Extremal Graph Theory, pp. 309ff.

LINKS

Table of n, a(n) for n=1..10.

CROSSREFS

Cf. A191873 A191874, A191966.

Sequence in context: A307699 A226485 A213638 * A173064 A111367 A105059

Adjacent sequences:  A191962 A191963 A191964 * A191966 A191967 A191968

KEYWORD

nonn,more

AUTHOR

R. H. Hardin and N. J. A. Sloane, Jun 18 2011

STATUS

approved

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Last modified October 17 16:34 EDT 2021. Contains 348065 sequences. (Running on oeis4.)