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A331639 Number of binary matrices with nonzero rows, a total of n ones and distinct columns each with the same number of ones and columns in decreasing lexicographic order. 2
1, 2, 2, 8, 2, 95, 2, 1062, 2651, 17667, 2, 946585, 2, 10422801, 126470568, 555727036, 2, 61345560608, 2, 1559456567421, 28383861400820, 19815939349521, 2, 30118264353296169, 8755909495925859, 49334805652369611, 21097628287362414244, 98053701052228556867, 2, 27303813269345643163251 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

The condition that the columns be in decreasing order is equivalent to considering nonequivalent matrices with distinct columns up to permutation of columns.

LINKS

Table of n, a(n) for n=1..30.

FORMULA

a(n) = Sum_{d|n} A331277(n/d, d).

a(p) = 2 for prime p.

CROSSREFS

Cf. A331277, A331638.

Sequence in context: A274139 A283995 A056189 * A121860 A283990 A021442

Adjacent sequences:  A331636 A331637 A331638 * A331640 A331641 A331642

KEYWORD

nonn

AUTHOR

Andrew Howroyd, Jan 23 2020

STATUS

approved

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Last modified January 16 13:57 EST 2022. Contains 350376 sequences. (Running on oeis4.)