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A099094 a(n)=3a(n-2)+3a(n-3), a(0)=1,a(1)=0,a(2)=3. 2
1, 0, 3, 3, 9, 18, 36, 81, 162, 351, 729, 1539, 3240, 6804, 14337, 30132, 63423, 133407, 280665, 590490, 1242216, 2613465, 5498118, 11567043, 24334749, 51195483, 107705376, 226590696, 476702577, 1002888216, 2109879819, 4438772379 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

COMMENTS

Diagonal sums of A099093.

LINKS

Table of n, a(n) for n=0..31.

Index to sequences with linear recurrences with constant coefficients, signature (0,3,3)

FORMULA

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

CROSSREFS

Sequence in context: A089892 A038221 A099465 * A222169 A222444 A206492

Adjacent sequences:  A099091 A099092 A099093 * A099095 A099096 A099097

KEYWORD

easy,nonn

AUTHOR

Paul Barry, Sep 25 2004

EXTENSIONS

Corrected by Philippe Deléham, Dec 18 2008

STATUS

approved

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Last modified December 20 06:03 EST 2014. Contains 252241 sequences.