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A280782 Number of irreducible matrices X of all sizes with nonnegative integral entries satisfying X^2 = nX. 1
1, 2, 6, 15, 42, 99, 262, 633, 1592, 3897, 9697, 23767, 58804, 144541 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Table of n, a(n) for n=1..14.

Jakob Zimmermann, Counting quasi-idempotent irreducible integral matrices, arXiv:1701.03699 [math.CO], 2017.

CROSSREFS

Cf. A280783.

Sequence in context: A121328 A139379 A236110 * A307308 A065178 A178936

Adjacent sequences:  A280779 A280780 A280781 * A280783 A280784 A280785

KEYWORD

nonn,more

AUTHOR

N. J. A. Sloane, Jan 20 2017

EXTENSIONS

Definition corrected by N. J. A. Sloane, Jan 23 2017 at the suggestion of Jakob Zimmermann

a(14) from Jakob Zimmermann, Jan 23 2017

STATUS

approved

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Last modified January 27 17:58 EST 2020. Contains 331296 sequences. (Running on oeis4.)