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A100138 Sum C(n-3k,3k)2^(n-5k), k=0..floor(n/6). 1
1, 2, 4, 8, 16, 32, 66, 144, 336, 832, 2144, 5632, 14852, 38968, 101312, 260736, 664704, 1681152, 4226056, 10578080, 26407648, 65838848, 164095360, 409129472, 1020795408, 2549137824, 6371133120, 15935185792, 39878810624, 99837958144 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

Binomial transform of 1,1,1,1,1,1,3,3,9,9,21,... with g.f. (1-x)^2(1+x)^2/(1-3x^2+3x^4-3x^6)=(1+x)(1-x^2)^2/((1-x^2)^3-2x^6).

LINKS

Table of n, a(n) for n=0..29.

Index entries for linear recurrences with constant coefficients, signature (6,-12,8,0,0,2).

FORMULA

G.f.: (1-2x)^2/((1-2x)^3-2x^6); a(n)=6a(n-1)-12a(n-2)+8a(n-3)+2a(n-6).

CROSSREFS

Cf. A052101, A100134.

Sequence in context: A210542 A141366 A049142 * A180208 A100139 A274860

Adjacent sequences:  A100135 A100136 A100137 * A100139 A100140 A100141

KEYWORD

easy,nonn

AUTHOR

Paul Barry, Nov 06 2004

STATUS

approved

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Last modified February 18 20:32 EST 2018. Contains 299330 sequences. (Running on oeis4.)