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Search: id:A143451
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| A143451 |
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Expansion of 1/(x^k*(1-x-2*x^(k+1))) for k=8. |
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+0
2
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| 1, 3, 5, 7, 9, 11, 13, 15, 17, 19, 25, 35, 49, 67, 89, 115, 145, 179, 217, 267, 337, 435, 569, 747, 977, 1267, 1625, 2059, 2593, 3267, 4137, 5275, 6769, 8723, 11257, 14507, 18625, 23811, 30345, 38619, 49169, 62707, 80153, 102667, 131681, 168931, 216553
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OFFSET
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0,2
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COMMENT
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a(n) is also the number of length n ternary words with at least 8 0-digits between any other digits.
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FORMULA
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G.f.: 1/(x^8*(1-x-2*x^9)).
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MAPLE
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a := proc(k::nonnegint) local n, i, j; if k=0 then unapply (3^n, n) else unapply ((Matrix(k+1, (i, j)-> if (i=j-1) or j=1 and i=1 then 1 elif j=1 and i=k+1 then 2 else 0 fi)^(n+k))[1, 1], n) fi end(8): seq (a(n), n=0..62);
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CROSSREFS
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8th column of A143453.
Sequence in context: A143452 A138217 A074775 this_sequence A014261 A066640 A137507
Adjacent sequences: A143448 A143449 A143450 this_sequence A143452 A143453 A143454
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KEYWORD
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nonn
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AUTHOR
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Alois P. Heinz (heinz(AT)hs-heilbronn.de), Aug 16 2008
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