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Search: id:A141244
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| A141244 |
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Numerators in expansion of (1-sqrt(1-x^2))/(1-x). |
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+0
2
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| 0, 0, 1, 1, 5, 5, 11, 11, 93, 93, 193, 193, 793, 793, 1619, 1619, 26333, 26333, 53381, 53381, 215955, 215955, 436109, 436109, 3518265, 3518265, 7088533, 7088533, 28539857, 28539857, 57414019
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OFFSET
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0,5
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COMMENT
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The denominators in the expansion of (1-sqrt(1-x^2))/(1-x) are 1,1,2,2,8,8,16,16,... or
2^A005187(n) doubled. The sequence 0,1/2,1/2,5/8,5/8,... is the image of n under the
Chebyshev related (rational) Riordan array c((x/2)^2),(x/2)c((x/2)^2)) with c(x) the g.f. of A000108.
The image of n+1 under this array is 1,1,1,....
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CROSSREFS
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Cf. A120778.
Sequence in context: A058610 A143427 A101203 this_sequence A121849 A164930 A098331
Adjacent sequences: A141241 A141242 A141243 this_sequence A141245 A141246 A141247
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KEYWORD
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easy,frac,nonn
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AUTHOR
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Paul Barry (pbarry(AT)wit.ie), Jun 17 2008
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