A099216 - OEIS

A099216

a(n)=4a(n-1)-4a(n-2)+2a(n-3).

1, 2, 4, 10, 28, 80, 228, 648, 1840, 5224, 14832, 42112, 119568, 339488, 963904, 2736800, 7770560, 22062848, 62642752, 177860736, 504997632, 1433833088, 4071063296, 11558916096, 32819077376, 93182771712, 264572609536

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OFFSET

0,2

COMMENTS

Binomial transform of tribonacci numbers A000213.

LINKS

Table of n, a(n) for n=0..26.

Index entries for linear recurrences with constant coefficients, signature (4,-4,2).

FORMULA

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

CROSSREFS

Cf. A099214, A099215, A055588.

Sequence in context: A106362 A271896 A148109 * A149819 A276051 A149820

Adjacent sequences: A099213 A099214 A099215 * A099217 A099218 A099219

KEYWORD

easy,nonn

AUTHOR

Paul Barry, Oct 06 2004

STATUS

approved