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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

%I #8 Jan 15 2020 18:41:57

%S 1,2,2,4,2,14,2,76,31,801,2,12797,2,233247,28480,5560377,2,160866915,

%T 2,5351339038,193927186,208746406130,2,9342273087807,5289613,

%U 470405726166256,4946464287635,26636935297440055,2,1679266767908385729,2,116818412262277969513

%N 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.

%C The condition that the rows be in nonincreasing order is equivalent to considering nonequivalent matrices up to permutation of rows.

%F a(n) = Sum{d|n} A331126(n/d, d).

%F a(p) = 2 for prime p.

%e The a(4) = 4 matrices are:

%e [1 0 0 0] [1] [1 0] [1 1]

%e [0 1 0 0] [1] [1 0] [1 0]

%e [0 0 1 0] [1] [0 1] [0 1]

%e [0 0 0 1] [1] [0 1]

%Y Cf. A331126.

%K nonn

%O 1,2

%A _Andrew Howroyd_, Jan 15 2020

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Last modified April 25 03:15 EDT 2024. Contains 371964 sequences. (Running on oeis4.)