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A027436 f(x) = Sum a(n)*x^n, n = 1..inf satisfies f(f(x)) = x*(1 + 4*x). 6
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; text; internal format)
OFFSET

0,3

LINKS

Table of n, a(n) for n=0..21.

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). - Vladimir Kruchinin, Nov 08 2011

CROSSREFS

Sequence in context: A102736 A247007 A103619 * A115125 A025225 A213010

Adjacent sequences:  A027433 A027434 A027435 * A027437 A027438 A027439

KEYWORD

sign

AUTHOR

Jonathan Deane

EXTENSIONS

Added a(0)=0 (sum in title starts at a(1)), Henry Bottomley, Apr 20 2011

STATUS

approved

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Last modified April 26 12:00 EDT 2019. Contains 322472 sequences. (Running on oeis4.)