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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 * A079242 A121860 A283990 Adjacent sequences: A331636 A331637 A331638 * A331640 A331641 A331642 KEYWORD nonn AUTHOR Andrew Howroyd, Jan 23 2020 STATUS approved

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Last modified August 9 01:26 EDT 2024. Contains 375024 sequences. (Running on oeis4.)