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A277433 Martin Gardner's minimal no-3-in-a-line problem, all slopes version. 3
1, 4, 4, 4, 6, 6, 8, 8, 8, 8 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

a(n) is the minimal number of counters that can be placed on an n X n grid, no three in a straight line, such that adding one more counter on any vacant grid point will produce three in a line.  Lines can have any slope.

The "queens" version of this problem, where lines are restricted to vertical, horizontal and diagonal, is A219760.

a(11) <= 10, a(12) <= 10.

LINKS

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

Robert Israel, Examples for n <= 12 (provably optimal for n <= 10).

CROSSREFS

Cf. A219760.

Sequence in context: A073229 A116446 A102126 * A219760 A097918 A256416

Adjacent sequences:  A277430 A277431 A277432 * A277434 A277435 A277436

KEYWORD

nonn,more

AUTHOR

Robert Israel, Oct 14 2016

STATUS

approved

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Last modified July 31 06:15 EDT 2021. Contains 346369 sequences. (Running on oeis4.)