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A158561
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a(n)=((2^n)*((2^n)+1) - (2^(n-1))*((2^(n-1))+1))/2, a(1)=3.
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0
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3, 7, 26, 100, 392, 1552, 6176, 24640, 98432, 393472, 1573376, 6292480, 25167872, 100667392, 402661376
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OFFSET
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1,1
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COMMENTS
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a(n) gives the number of elements with the length of n-digits, base B, in the addition matrix <0;B^n -1> x <0;B^n -1>. a(1)=B*(B+1)/2. a(n)=((B^n)*((B^n)+1) - (B^(n-1))*((B^(n-1))+1))/2.
Essentially the same as A049775. [From R. J. Mathar, Mar 26 2009]
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LINKS
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Table of n, a(n) for n=1..15.
Index to sequences with linear recurrences with constant coefficients, signature (6,-8)
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FORMULA
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x*(1-x)*(3-8*x)/((1-2*x)*(1-4*x)) [From Jaume Oliver Lafont, Mar 27 2009]
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CROSSREFS
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Cf. A000217
Cf. A006516. [From Jaume Oliver Lafont, Mar 27 2009]
Sequence in context: A215018 A069738 A057005 * A108217 A120120 A126472
Adjacent sequences: A158558 A158559 A158560 * A158562 A158563 A158564
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KEYWORD
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easy,nonn
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AUTHOR
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Ctibor O. Zizka, Mar 21 2009
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STATUS
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approved
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