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A027436
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f(x) = Sum a(n)*x^n, n = 1..inf satisfies f(f(x)) = x*(1 + 4*x).
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5
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0, 1, 2, -4, 16, -80, 432, -2304, 10944, -35328, -74112, 2736384, -30853632, 238663680, -1247457280, 2201247744, 32530722816, -320650199040, 156266184704, 18314630348800, -20667999748096, -3428200020508672
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,3
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FORMULA
| a(n)=4^(n-1) * A097088(n) / 2^A097089(n).
T(n,m) = if n=m then 1 else (binomial(m,n-m)*4^(n-m)-sum(i=m+1..n-1, T(n,i)*T(i,m)))/2. a(n) = T(n,1). [From Vladimir Kruchinin, Nov 08 2011]
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CROSSREFS
| Sequence in context: A058926 A102736 A103619 * A115125 A025225 A000831
Adjacent sequences: A027433 A027434 A027435 * A027437 A027438 A027439
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KEYWORD
| sign
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AUTHOR
| ees1jd(AT)ee.surrey.ac.uk (Jonathan Deane)
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EXTENSIONS
| Added a(0)=0 (sum in title starts at a(1)), Henry Bottomley, Apr 20 2011.
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