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A099214 a(n)=4a(n-1)-4a(n-2)+4a(n-3). 3
1, 2, 4, 12, 40, 128, 400, 1248, 3904, 12224, 38272, 119808, 375040, 1174016, 3675136, 11504640, 36014080, 112738304, 352915456, 1104764928, 3458351104, 10826006528, 33889681408, 106088103936, 332097716224, 1039597174784 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

Binomial transform of A099213.

LINKS

Table of n, a(n) for n=0..25.

FORMULA

G.f.: (1-2x)/((1-2x)^2-4x^3); a(n)=sum{k=0..floor(n/3), binomial(n-k, 2k)4^k*2^(n-3k)}.

CROSSREFS

Cf. A073724.

Sequence in context: A170810 A170809 A170808 * A126946 A113179 A214761

Adjacent sequences:  A099211 A099212 A099213 * A099215 A099216 A099217

KEYWORD

easy,nonn

AUTHOR

Paul Barry, Oct 06 2004

STATUS

approved

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Last modified November 27 20:49 EST 2021. Contains 349395 sequences. (Running on oeis4.)