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 A331391 Number of binary matrices with a total of n ones, distinct columns each with the same number of ones and nonzero rows in nonincreasing lexicographic order. 1
 1, 2, 2, 4, 2, 14, 2, 76, 31, 801, 2, 12797, 2, 233247, 28480, 5560377, 2, 160866915, 2, 5351339038, 193927186, 208746406130, 2, 9342273087807, 5289613, 470405726166256, 4946464287635, 26636935297440055, 2, 1679266767908385729, 2, 116818412262277969513 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS The condition that the rows be in nonincreasing order is equivalent to considering nonequivalent matrices up to permutation of rows. LINKS FORMULA a(n) = Sum{d|n} A331126(n/d, d). a(p) = 2 for prime p. EXAMPLE The a(4) = 4 matrices are:    [1 0 0 0]   [1]   [1 0]   [1 1]    [0 1 0 0]   [1]   [1 0]   [1 0]    [0 0 1 0]   [1]   [0 1]   [0 1]    [0 0 0 1]   [1]   [0 1] CROSSREFS Cf. A331126. Sequence in context: A126984 A159749 A227293 * A102416 A333595 A227509 Adjacent sequences:  A331388 A331389 A331390 * A331392 A331393 A331394 KEYWORD nonn AUTHOR Andrew Howroyd, Jan 15 2020 STATUS approved

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Last modified April 23 13:51 EDT 2021. Contains 343204 sequences. (Running on oeis4.)