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 A331640 Number of binary matrices with n columns and any number of distinct nonzero rows with 2 ones in every column. 3
 1, 0, 6, 120, 6174, 449520, 49686726, 7455901320, 1479839874414, 373573957133280, 117097298726892246, 44596327028174342520, 20287402287658565190654, 10864410524883717498300240, 6765647366010527963979060966, 4847736403559133115838948559720 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,3 LINKS Andrew Howroyd, Table of n, a(n) for n = 0..200 EXAMPLE The a(2) = 6 matrices are:    [1 1]  [1 1]  [1 0]  [1 0]  [0 1]  [0 1]    [1 0]  [0 1]  [1 1]  [0 1]  [1 1]  [1 0]    [0 1]  [1 0]  [0 1]  [1 1]  [1 0]  [1 1] CROSSREFS Row n=2 of A331567. Cf. A331641. Sequence in context: A093910 A002370 A012846 * A012641 A012795 A054479 Adjacent sequences:  A331637 A331638 A331639 * A331641 A331642 A331643 KEYWORD nonn AUTHOR Andrew Howroyd, Jan 23 2020 STATUS approved

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Last modified November 29 21:32 EST 2021. Contains 349416 sequences. (Running on oeis4.)