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Search: id:A118871
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| A118871 |
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Number of binary sequences of length n containing exactly one subsequence 0101. |
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+0
2
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| 0, 0, 0, 0, 1, 4, 10, 24, 57, 128, 278, 596, 1260, 2628, 5430, 11136, 22683, 45936, 92574, 185764, 371347, 739840, 1469580, 2911224, 5753048, 11343800, 22322444, 43845120, 85973013, 168314604, 329041842, 642385248, 1252552077, 2439430272
(list; graph; listen)
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OFFSET
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0,6
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COMMENT
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With only two 0's at the beginning, the convolution of A112575 with itself. Column 1 of A118869.
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FORMULA
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G.f.=z^4/(1-2z+z^2-2z^3+z^4)^2.
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EXAMPLE
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a(5)=4 because we have 01010,01011,00101, and 10101.
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MAPLE
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g:=z^4/(1-2*z+z^2-2*z^3+z^4)^2: gser:=series(g, z=0, 40): seq(coeff(gser, z, n), n=0..35);
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CROSSREFS
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Cf. A118869, A118870, A112575, A118430.
Sequence in context: A087447 A129953 A079859 this_sequence A019494 A079844 A080617
Adjacent sequences: A118868 A118869 A118870 this_sequence A118872 A118873 A118874
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KEYWORD
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nonn
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AUTHOR
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Emeric Deutsch (deutsch(AT)duke.poly.edu), May 03 2006
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