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A052549 a(0)=1; a(n) = 5*2^(n-1) - 1, n>0. 7
1, 4, 9, 19, 39, 79, 159, 319, 639, 1279, 2559, 5119, 10239, 20479, 40959, 81919, 163839, 327679, 655359, 1310719, 2621439, 5242879, 10485759, 20971519, 41943039, 83886079, 167772159, 335544319, 671088639, 1342177279, 2684354559 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

A153894 is a better version of this sequence. - N. J. A. Sloane, Feb 07 2009

Equals binomial transform of [1, 3, 2, 3, 2, 3, 2,...] and row sums of triangle A140183. - Gary W. Adamson, May 11 2008

LINKS

Table of n, a(n) for n=0..30.

INRIA Algorithms Project, Encyclopedia of Combinatorial Structures 486

Index entries for linear recurrences with constant coefficients, signature (3,-2).

FORMULA

G.f.: -(-x+x^2-1)/((-1+2*x)*(-1+x)).

-2*a(n) + a(n+1) - 1 = 0, n>0.

Row sums of triangle A133601. - Gary W. Adamson, Sep 18 2007

MAPLE

spec := [S, {S=Prod(Sequence(Union(Z, Z)), Union(Z, Sequence(Z)))}, unlabeled]: seq(combstruct[count](spec, size=n), n=0..20);

MATHEMATICA

a=4; lst={1, a}; k=5; Do[a+=k; AppendTo[lst, a]; k+=k, {n, 0, 5!}]; lst (* Vladimir Joseph Stephan Orlovsky, Dec 15 2008 *)

CROSSREFS

Cf. A133601, A140183, A153894.

Sequence in context: A008135 A009885 * A153894 A214318 A034479 A183304

Adjacent sequences:  A052546 A052547 A052548 * A052550 A052551 A052552

KEYWORD

easy,nonn

AUTHOR

encyclopedia(AT)pommard.inria.fr, Jan 25 2000

EXTENSIONS

More terms from James A. Sellers, Jun 06 2000

STATUS

approved

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Last modified November 21 13:53 EST 2017. Contains 295001 sequences.