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A275779
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a(n) = (2^(n^2) - 1)/(1 - 1/2^n).
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2
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2, 20, 584, 69904, 34636832, 69810262080, 567382630219904, 18519084246547628288, 2422583247133816584929792, 1268889750375080065623288448000, 2659754699919401766201267083003561984, 22306191045953951743035482794815064402563072
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OFFSET
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1,1
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COMMENTS
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Sum of the geometric progression of ratio 2^n.
Number of all partial binary matrices with rows of length n: A partial binary matrix has 1<=k<=n rows of length n. The number of different partial matrices with k rows is 2^(k*n). a(n) is the sum for k between 1 and n.
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LINKS
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FORMULA
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a(n) = Sum_{k=1..n} 2^(k*n).
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MATHEMATICA
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Table[(2^(n^2) - 1)/(1 - 1/2^n), {n, 1, 10}]
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PROG
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(PARI) a(n) = {(2^(n^2) - 1)/(1 - 1/2^n)} \\ Andrew Howroyd, Apr 26 2020
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CROSSREFS
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Cf. A128889 (accepting the null matrix and excluding the full n*n matrices)
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KEYWORD
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nonn,easy
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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