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A263677 Irregular table read by rows, n >= 1, k >= 0: T(n,k) is the number of binary symmetric n X n matrices with k holes that are squares, where the axes of symmetry are horizontal and vertical. 1
1, 1, 3, 1, 3, 1, 28, 15, 11, 0, 6, 3, 30, 16, 0, 0, 3, 3 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

COMMENTS

Inspired by A258643 but the axes of symmetry are the same as in A262742. The mirror patterns and nonsquare holes are excluded.

LINKS

Table of n, a(n) for n=1..18.

Kival Ngaokrajang, Illustration of initial terms

EXAMPLE

Irregular table begins:

n\k  0  1  2  3  4  5 ...

1    1

2    1

3    3  1

4    3  1

5   28 15 11  0  6  3

6   30 16  0  0  3  3

...

CROSSREFS

Cf. A258643, A262742.

Sequence in context: A262940 A278601 A281038 * A099906 A262026 A270390

Adjacent sequences:  A263674 A263675 A263676 * A263678 A263679 A263680

KEYWORD

nonn,tabf,more

AUTHOR

Kival Ngaokrajang, Oct 23 2015

STATUS

approved

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Last modified October 16 16:34 EDT 2019. Contains 328101 sequences. (Running on oeis4.)