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Search: id:A120617
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| A120617 |
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Hankel transform of g.f. 1/sqrt(1+4x^2). |
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+0
5
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| 1, -2, -4, 8, 16, -32, -64, 128, 256, -512, -1024, 2048, 4096, -8192, -16384, 32768, 65536, -131072, -262144, 524288, 1048576, -2097152, -4194304, 8388608, 16777216, -33554432, -67108864, 134217728, 268435456, -536870912, -1073741824, 2147483648, 4294967296, -8589934592
(list; graph; listen)
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OFFSET
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0,2
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COMMENT
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Hankel transform of e.g.f. Bessel_I(0,2*sqrt(-1)*x) or (1,0,-2,0,6,0,-20,...). Hankel transform of sum{k=0..n, (-1)^(n-k)*C(n,k)^2}. Hankel transform of A098331.
Hankel transform of A082590. [From Paul Barry (pbarry(AT)wit.ie), Apr 26 2009]
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FORMULA
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G.f.: (1-2x)/(1+4x^2); a(n)=2^n*(cos(pi*(n+1)/2)+sin(pi*(n+1)/2))
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CROSSREFS
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Sequence in context: A084633 A122803 A000079 this_sequence A050732 A138815 A103662
Adjacent sequences: A120614 A120615 A120616 this_sequence A120618 A120619 A120620
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KEYWORD
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easy,sign
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AUTHOR
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Paul Barry (pbarry(AT)wit.ie), Jun 17 2006
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